Encyclopedia of Japanese Minerals (Go to Intro Page)
by Alfredo Petrov
Minerals Starting with "M"
MAGHEMITE (ji-seki-tekkoh)
Nara: Submetallic grey maghemite occurs as "lodestone" (with magnetic polarity) in decimeter-size masses formed by weathering of magnetite veins in contact metamorphic rock at the Dorogawa-Goyoumatsu mine.
Okinawa: As dark brown, sharp pseudomorphs after striated pyrite cubes at Uebara, abundantly in stream sand. Some are almost pure maghemite, while others are a mixture of goethite and maghemite.
Yamaguchi: A secondary oxidation product of magnetite, associated with hematite, lepidocrocite and goethite, at the Kumano iron mine, in metasomatic ore at the contact between limestone and quartz diorite. Analysis (as wt% of oxides) gave Fe''' 75.95, Fe'' 22.10, Si 1.02, Al 0.51, Mg 0.10, Mn'' 0.08, Ca tr, Ti nil, water nil (Shibuya, 1958; in DHZ 5).
MAGNESIO-ARFVEDSONITE (kudo-arubezon-senseki)
Ehime: Dark green or dark blue to blackish vitreous translucent crystals as thin prisms to 3mm long at Irazuyama, in flaky friable white mica-quartz schist.
Iwate: At the Nodatamagawa mine, as pale greenish brown cleavages to 5mm, with neotocite in massive pink manganese ore. Yellowish-orange aggregates (with 0.31 apfu K replacing Na) form bands in braunite-rhodonite-nambulite ore at the Tanohata mine.
MAGNESIOCHROMITE (kuromu-kudo-koh)
(Some unanalyzed material loosely classed under "chromite" is ferroan magnesiochromite and belongs here.)
Hokkaido: Irregular masses in clinopyroxene cumulates in serpentine at the confluence of the Penkemotou with the Mukawa river, (Mg 0.65, Fe 0.27, Ca 0.08)(Cr 1.37, Al 0.37, Fe 0.26) O4, were originally reported as "chromite". Much of the so-called "chromite" from this district (including that from the Tomiuchi mine?) is probably magnesiochromite. Masses from serpentine at Panke-Iyaputeushi nearby, which has thin coatings of grass-green "chrome ochre", are roughly on the chromite-magnesiochromite boundary. Also from the Nukahira mine and the Kasuga mine.
Shizuoka: "Chromite" from serpentinite at the Hiroosa mine is really magnesiochromite. Analysis gave (Mg 4.59, Fe'' 3.46, Mn'' 0.07) (Cr 10.48, Al 4.15, Fe''' 1.16, Si 0.09) O 32 (Kitahara, 1954; in DHZ 5). Also at the Hironaga mine (same place???).
Tottori: Black granular aggregates of Al-rich magnesiochromite form ovoid "beans" to 2cm richly embedded in pale tan rock in the Wakamatsu mine, in the Tari-Misaka ultramafic complex, where they were mined as low-grade chromium ore. (Some of the material here is chromian hercynite.) Also from the Hino mine.
MAGNESIOFERRITE (ji-kudo-tekkoh)
(Some of the material listed under "magnetite" may well be ferroan magnesioferrite.)
Hokkaido: A major component of magnesioferrite-olivine rock in the alpine-type Iwanai-dake peridotite mass. A product of metasomatic alteration rather than a primary magmatic mineral.
MAGNESIOFOITITE (kudo-foito-denki-seki) (= IMA # 98-037)
Miyazaki: Aesthetic spheroidal microsprays, to 1mm across, of filiform magnesiofoitite line vugs at Hinokage. The tiny crystals are whitish to greenish white or greenish grey. Occasionally coat colorless quartz crystals in great abundance, such specimens looking to the naked eye like mouldy quartz.
Yamanashi: Pale bluish grey to pale brownish gey and grey-green, acicular micro-sprays and felty masses of magnesiofoitite are found in solution vugs a few cm wide in andesite and dacite which were highly altered by acid hot springs in a fissure zone at Kyonosawa, the type locality for this increasingly common tourmaline species. Magnesiofoitite is the magnesium analogue of foitite, with much Al and minor ferrous iron replacing Mg in the Y-site, and minor Na in the X-site. Individual needles reach a maximum 1.5mm long and 15 microns wide, and are pleochroic grey-blue and pale lavender. Associated with quartz, pale violet dumortierite, white kaolinite, microcrystals of rutile, and pyrite nodules.
MAGNESIOHORNBLENDE (kudo-futsuu-kaku-senseki)
Fukushima: As aggregates of black prismatic crystals in gabbroic pegmatite at Jitsusawa. Some (all?) of the so-called "ferrohornblende" from clinopyroxene amphibolite at Yamatama is actually slightly Mg-dominant (considering only divalent Fe), with empirical formula (Ca 1.83, Na 0.37, K 0.06) (Mg 2.25, Fe'' 2.01, Al 0.37, Fe''' 0.32, Ti 0.13, Mn'' 0.04) (Si 6.81, Al 1.19) O 22 (OH) 1.91 (Shidou, F. (1958) Journ. Fac. Sci., Univ. Tokyo, sec. II, 11: 131). Clinopyroxene amphibolite in Furudono-mura yields iron-rich hornblende with empirical formula (Ca 1.89, Na 0.23, K 0.09) (Mg 2.16, Fe'' 2.08, Al 0.68, Fe''' 0.15, Ti 0.14, Mn'' 0.06) (Si 6.62, Al 1.38) O 22 (OH) 1.66 (includes 0.12 wt% P2O5) (Miyashiro, A. (1958) Journ. Fac. Sci. Univ. Tokyo, section 2, 11: 219). "Tschermakitic hornblende" in medium-grained gneissose quartz diorite from this same village gave (Ca 1.48, Na 0.50, K 0.15) (Mg 2.16, Fe'' 1.70, Al 1.17, Fe''' 0.60, Ti 0.09, Mn'' 0.07) (Si 6.18, Al 1.82) O 22 (OH) 2.03 (with 0.10 wt% P2O5) (Ogura Y. (1958) Jap. Journ. Geol. Geogr., 29:171).
Gumma: Magnesiohornblende is common in Sambagawa amphibole schists of the Shibukawa district, from where it was originally described as "edenite". Two reanalyses gave the empirical formulae (Ca 1.66, Na 0.64, K 0.06) (Mg 3.02, Fe'' 1.29, Al 0.65, Fe''' 0.10, Ti 0.07, Mn'' 0.02) (Si 6.95, Al 1.05) O 22 (OH) 1.85 (with 0.006 wt% P2O5) and (Ca 1.66, Na 0.55, K 0.08) (Mg 2.19, Fe'' 1.29, Al 0.75, Fe''' 0.38, Ti 0.11, Mn'' 0.02) (Si 7.03, Al 0.97) (O 21.84, OH 0.16) (OH) 2.00 (with 0.005 wt% P2O5) (Seki, Y., et al. (1959) Jap. Journ. Geol. Geogr., 30; 233; Leake, B.E. (1962) Jap. Journ. Geol. Geogr., 33: 1). Also at Shimo'ohya.
Hokkaido: Magnesiohornblende from diorite in Esashi gave (Ca 1.72, Na 0.33, K 0.13) (Mg 2.43, Fe'' 1.70, Fe''' 0.66, Ti 0.18, Al 0.14, Mn'' 0.04) (Si 7.32, Al 0.68) O 22 (OH) 1.32 (Harada, Z. (1948) Journ. Fac. Sci. Hokkaido Univ., series 4, 8, 289).
Ibaragi: Magnesiohornblende in basic hornblende schist in Sekimoto-mura gave the empirical formula (Ca 2.02, Na 0.16, K 0.05) (Mg 3.05, Fe'' 1.56, Al 0.28, Fe''' 0.11, Ti 0.09, Mn'' 0.04) (Si 7.14, Al 0.86) O 22 (OH) 1.78; also includes 0.22 wt% P2O5. Another, much more iron-rich, from Hatatate-tohge in the same village, gave (Ca 1.79, Na 0.30, K 0.03) (Mg 2.41, Fe'' 2.14, Al 0.47, Fe''' 0.11, Ti 0.09, Mn'' 0.04) (Si 6.97, Al 1.03) O 22 (OH) 1.85; with 0.09 wt% P2O5. (Shidou, F. & Miyashiro, A., 1959).
Ishikawa: Hakusan volcano.
Kouchi: Pargasitic hornblende is a major component garnet-clinopyroxene amphibolite from the Kurosegawa tectonic zone near Kouchi city.
Kumamoto: At Goou-tohge, euhedral, sharp, loose magnesiohornblende crystals to 3cm weather out of hornblende-augite-hypersthene andesite lava from Tawara-yama on the rim of the Aso caldera. The surface of these crystals is usually altered to an opaque mixture of magnetite and augite, and partially coated with a light brown film.
Nagano: Black prismatic xls to 2cm as phenocrysts in andesite at Tonoshiro. Similarly, short prismatic xls to 1cm as phenocrysts in andesite at Eimyousan. Also at Fujimi.
Nagasaki: Unzendake.
Niigata: Reported as "edenitic hornblende" with jadeite in albitite rock from Kotaki, empirically (Ca 1.54, Na 0.92, K 0.02) (Mg 4.05, Al 0.57, Fe'' 0.42, Fe''' 0.17, Mn'' 0.01, Ti 0.01) (Si 7.13, Al 0.87) O 22 (OH) 1.63 (with 0.05 wt% P2O5) (Shidou, F. (1958) Journ. Geol. Soc. Japan, 64: 595).
MAGNESIORIEBECKITE (kudo-riibekku-senseki)
Niigata: Pale bluish grey to greyish blue, sometimes dark blue, magnesioriebeckite is found as fibrous masses in white albite rock, associated with quartz, strontio-orthojoaquinite and rare ohmilite, benitoite or leucosphenite in whitish riebeckite-syenite or albitite bodies in serpentine at Kanayama-dani and elsewhere around Hashidate. Ohmi district glaucophane schists are limited to the chlorite metamorphic facies, with the dominant amphibole being intermediate glaucophane-magnesioriebeckite.
Saitama???: Magnesioriebeckite in chlorite-epidote-albite schist at Fuppu in Akuwara-mura in the Kanto Mts. gave an empirical formula (Na 1.56, Ca 0.30, K 0.04) (Mg 1.62, Fe'' 0.91, Mn'' 0.01) (Fe''' 1.45, Al 0.45, Ti 0.04) (Si 7.91, Al 0.09) O 22 (OH) 2.93 (Seki, Y. (1958) Jap. Journ. Geol. Geogr., 29, 233). (In the regionally metamorphosed schists of the Kanto Mts., magnesioriebeckite characterizes a higher metamorphic grade, with glaucophane being the primary amphibole in lower grades.)
Tokushima: Mt Bizan might be considered the type locality for magnesioriebeckite, since the name was first used (by Miyashiro in 1957) for material from the crystalline schists here. It is extremely pleochroic (blue; very pale yellow), and has more Mn and Ca than magnesioriebeckite from other localities (wt%: MgO 11.98, FeO 3.53, CaO 1.95, MnO 1.25). Also at Suberidani.
MAGNESIOSADANAGAITE (kudo-sadanaga-senseki)
Ehime: (See under "Potassic-magnesiosadanagaite" for the material originally described as "magnesiosadanagaite" (IMA# 1982-102).)
Gifu: True magnesiosadanagaite (as opposed to the potassic-magnesiosadanagaite which had been originally described as "sadanagaite") occurs as black-brown or brownish black aggregates in dolomite skarn, near the contact with the Kaizuki-yama granite, at the Kawai open pit of the Kasuga dolomite-wollastonite mine. Elsewhere in Kasuga-mura, reported at Mitsuka as orange-brown zones to 0.3mm thick around long prismatic glassy sadanagaite crystals to 4mm. Also in the cores of pargasite balls in hornfels in Kawai-mura (or Kawai pit in Kasuga-mura?). As brownish black, sharply bounded Al-rich rims of intermediate magnesiosadanagaite-pargasite about 0.15mm thick around Al-poor pargasite cores of prismatic crystals to 3mm in contact aureole; associated with phlogopite, titanite, calcite, pyrrhotite, chalcopyrite. Complete isomorphous series to sadanagaite. (Streak brown with reddish tint; non-fluorescent; vitreous luster; brittle; perfect {110} cleavage; H 5.5-6; uneven fracture; D 3.17-3.18; under polarized light, strongly pleochroic pale yellow to reddish brown.) (Known already in 1984 but, because of the reorganization of "sadanagaite" minerals, not formally accepted by the IMA until 2003.)
MAGNESITE (ryoh-kudo-seki; ryoh-kudo-koh)
Hyougo: Yellow lenticular crystals in mammillary aggregates to several cm at the Nakase mine.
Ibaragi: Sporadic single crystals in talc schist at Kamesaku. Earthy white magnesite at Machiya.
Ishikawa: Aggregates of grey rounded grains about 2mm diameter, on ore minerals at the Kuradani mine.
Wakayama: Colorless, equant rhombic magnesite crystals to 4mm occur on druses of thin lenticular whitish dolomite crystals in Yuasa-cho.
MAGNETITE (ji-tekkoh)
(Some unanalyzed material loosely classed under "magnetite" may actually be ferroan magnesioferrite.)
Aomori: Vanadian magnetite (1 or 2% V oxide) was produced commercially, many tens of thousands of tons yearly, from ocean beach placers at the Misawa; Noushi and Sabishiro deposits in the Kamikita and Shimokita districts.
Chiba: Magnetite was mined on a large scale from ocean beach placers at the Iioka and Shinobuzaka deposits.
Ehime: As thin layers in cupriferous pyrite ore at the Besshi mine, with rare single crystals in quartz vugs.
Fukuoka: Crystals in complex habits to over 2cm at Sannotake, although good sharp ones were uncommon and most crystals from here exhibit "melted"-looking faces. Magnetite of a peculiar foliated habit occurs as masses to over 8cm on Jishakuyama ("Magnet Mountain") in Tagawa city. Flattened spinel-law twins of magnetite are aggregated as beautiful "iron roses"(!) to 1.5cm, most unusual for magnetite, at the Yobuno-Higashitani mine.
Fukushima: As hedenbergite-garnet-chalcopyrite-magnetite skarn by a granodiorite contact at the Yaguki mine (qv babingtonite). Remarkably close to end-member composition, a magnetite from the contact metasomatic Takanokura mine deposit gave (as oxide wt%) Fe''' 68.95, Fe'' 30.82, Al 0.19, Ca 0.02 (Takeuchi & Nambu, 1958; in DHZ 5).
Hokkaido: Rounded octahedra of magnetite to 7mm are dispersed through a brownish pink schist at Mitsuishi. As pebbles from a placer gold deposit at Onnenai. Large quantities of magnetite were extracted from ocean beach placers at the Funkawan; Kitatoyotsu; Kunnui; Menagawa; Nakanosawa; and Shirigishinai deposits.
Hyougo: Spheroidal magnetite with nickeline at the Natsume mine.??????????
Iwate: Octahedral or rhombic dodecahedral black xls to 2cm, faces varying from brilliant to dull, form coarse granular aggregates in andradite-epidote masses in contact metamorphosed iron skarns near granite contact at the Kamaishi mine, JapanÕs best source for magnetite specimens in the past. More complex crystals occur in the Shin-Taneyama and Sahinai orebodies here. Also from the Akagane mine. Pleistocene iron sands, slightly vanadian, were exploited at the Kawasaki-Kuji mine.
Mie: Chromian magnetite - (Fe 1.06, Mg 0.07) (Fe 1.20, Cr 0.27, Al 0.24, Ti 0.15) O4 - forms crystal rims surrounding cores of ferrian "ferritchromite" - (Fe 0.67, Mg 0.34) (Cr 0.73, Fe 0.71, Al 0.51) O4 - associated with ilmenite, andradite and ilvaite (qv) in fibrous mats of chrysotile and diopside which replace olivine in serpentinized peridotite in the Asama-gatake layered intrusion. The magnetite-chromite is frequently intergrown with ilmenite.
Nagasaki: Sharp octahedral xls to 1cm, or modified truncated octahedra to 2cm, as porphyroblasts in green talc schist or chlorite schist at Ougushi. In collections usually seen as matrix-free floaters extracted from weathered red clay by panning.
Nara: Magnetite veins in contact metamorphic rock at the Goyoumatsu mine, mined for use as a radiation barrier in nuclear power plants. Weathers to maghemite. Also worked from an andradite-bearing skarn on Gyojagaeri-dake ((either the same place or very nearby)).
Okayama: Somewhat lustrous crystals to 4cm form large aggregates in skarn at the Sampoh mine. Rough octahedral crystals to 1cm form coarse aggregates at Shitouyouze.
Saitama: Simple rhombic dodecahedrons form granular aggregates in a contact iron deposit (skarn) at the Chichibu mine, between Permian limestone and a Tertiary granodiorite intrusion; also in the Wanabasawa section here, with minor calcite. In a contact iron deposit at Nakatsugawa as octahedral xls to 8mm forming granular aggregates associated with prismatic actinolite xls. Simple isolated octahedrons embedded in chlorite schist in Minano-machi.
Shimane: Tertiary vanadian iron sand deposits of small extent at the Kumura and Konan mines. Average 0.46% V pentoxide.
MALACHITE (kujaku-ishi; kujaku-seki)
Akita: At the Arakawa mine, botryoidal incrustations of deep green, beautiful fibrous tufts of malachite crystals with silky luster, associated with cuprite, pyromorphite, brochantite, chrysocolla and cyanotrichite on chalcopyrite and quartz xls in fractures in oxidized chalcopyrite-pyrite-sphalerite-galena ore. Botryoidal malachite crusts associated with small tabular azurite xls in cavities at the Kisamori mine. Botryoidal crusts of compact massive malachite, with botryoids to 5cm, some with runny drip-like surface features, on crystalline quartz in cavities in oxidized chalcopyrite ore at the Ani mine. Botryoidal incrustations and deep green radial fibrous aggregates in a chalcopyrite-pyrite-quartz vein at the Hisaichi mine. In the large limonitic oxide zone of the Osarizawa mine.
Okayama: At the Mihara mine, radial aggregates of short hexagonal prismatic xls less than 1mm long are associated with azurite in fractures in an oxidized contact copper deposit.
Toyama: Reported as smooth light blue-green spherules to 1.5mm, sprinkled over colorless smithsonite at the Kamegai mine. (really aurichalcite???)
Yamaguchi: At the Naganobori mine, beautiful sprays of acicular green crystals scattered on black ore. Also from the Ohta mine (= Naganobori mine??). And at the Yamato copper mine.
MALAYAITE (maraya-seki)
Miyazaki: As massive white grains up to 1cm wide, embedded in brown rock at the Toroku mine. Bright yellow fluorescence under UV. Also at the Mitate mine.
Shimane: Associated with green garnet, both in garnet-wollastonite skarn and in the adjacent marble host rock, in the upper and middle parts of the Maruyama orebody of the Tsumo mine.
Yamaguchi: Glassy greyish brown to grey, euhedral to subhedral crystals, fluorescent bright yellow under UV light, are associated with cassiterite and quartz in hedenbergite skarn in the Iwaya orebody of the Kuga mine, a pyrometasomatic scheelite-sphalerite-chalcopyrite-pyrrhotite deposit replacing a limestone lens in chert. Malayaite also occurs embedded in skarn at the Kiwada scheelite mine, as golden crystals to 1mm, but is uncommon there.
MALDONITE (marudon-koh)
Kagoshima: In an Au-Bi-W-bearing quartz-tourmaline vein at the Tsugahira (Togahira) mine; related to a Miocene granitic intrusion.
MANGANAXINITE (mangan-ono-ishi)
Kouchi: At the Ananai manganese mine. Some material here is chemically close to the boundary between manganaxinite and tinzenite (qv).
Kyoto: Tamaiwa mine.
Miyazaki: Dark brown "manganaxinite" crystals to 3cm are reported (Anthony-Bideaux) from Takachiho (Toroku mine), (but these might be either ferroaxinite? Or manganaxinite from the Obira mine in Ouita?)
Ouita: Dark brown transparent "ferroaxinite" at the Obira mine can contain up to 5.2% Mn, so some of it is actually manganese dominant. An analysis of brownish grey axinite from here clearly corresponds to manganaxinite: (Ca 1.88, Mn'' 0.12) (Mn'' 0.74, Fe'' 0.23, Mg 0.030)... apfu (Ozaki, M. (1969) Sci. Reports, Fac. Sci. Kyushu Univ., 9, 129-142). Rare greenish to epidote-green axinite from the Shohdo orebody here is thought by local collectors to be almost pure manganaxinite (See under ferroaxinite for description.)
Tochigi: Blue-green manganaxinite occurs at the Takanosu mine.
Yamaguchi: Kusugi mine.
MANGANBERZELIITE (mangan-beruzeriusu-seki)
Fukushima: Rare yellow glassy granular-crystalline masses in metamorphosed sedimentary manganese ore at the Gozaisho mine.
MANGANITE (sui-mangan-koh)
Aomori: As aggregates or druses of semimetallic black, slender prismatic crystals to 1cm in cavities in sedimentary manganese ore at the Ouwani mine. At the nearby Hayaseno mine, short prismatic manganite crystals altered to pyrolusite are found in vugs in veins crossing Miocene rhyolite and rhyolitic tuff.
Hokkaido: Shiny botryoidal aggregates, with individual botryoids to 5cm, were precipitated from a warm spring in a sedimentary manganese deposit at the Meppu mine. Brilliant metallic crystals to 4mm form aggregates at the Chiwase (Chibase) mine. Also at the Yunosawa mine and the Pirika mine.
Kyoto: At the Ouetani mine, druses of brilliant manganite xls to 0.5mm line vugs to several cm across in massive submetallic manganese ore.
MANGANOCOLUMBITE (mangan-korunbu-seki)
Fukuoka: In lepidolite-rich pegmatite in biotite granite at Nagatare. (Manganotantalite and ferrotantalite also occur here.)
Fukushima: Reported from the Ishikawa district, but much of the "columbite" from these pegmatites is ferrocolumbite.
MANGANOCUMMINGTONITE (mangan-kaminton-senseki; chirodi-senseki)
(Note: The alkali-bearing "tirodite" reported from some japanese manganese deposits might now be classified as PARVOWINCHITE rather than manganocummingtonite.)
Fukushima: "Tirodite" at the Gozaisho mine forms yellowish brown bundles of small silky needles, with bluish black hematite grains.
Hokkaido: Abundant ore mineral at Tatehira, with Mn-pyroxene and quartz in hornfels created by low-pressure metamorphism of Mn-rich pelitic sediments.
Miyazaki: "Tirodite" at the Shimozuru mine.
Yamaguchi: A cummingtonite with 14.8% MnO was described from a manganese deposit. (Yoshimora, T. and Shirohzu, H. (1947) Journ. Geol. Soc. Japan, 53, 59) ((Where???))
MANGANOGRUNERITE (mangan-guryuneru-senseki; dannemora-senseki)
Tochigi: A major ore mineral, together with rhodonite and spessartine, in metasedimentary Paleozoic Mn ore at the Kyuurazawa mine. Also at the Kaso manganese mine.
MANGANOSITE (ryoku-mangan-koh)
(Manganosite crystals from the numerous japanese meta-sedimentary Mn deposits are almost invariably partially replaced by hausmannite around their edges and along interior fractures. Oxidation causes specimens in collections to quickly lose their emerald green color.)
Gifu: From metasedimentary Mn ore in Paleozoic chert at 8m depth in the Fukutomi mine, an interesting sample of supposedly oxidized "chocolate ore" (generally considered to be mostly hausmannite) was found (by XRD) to be almost entirely very fine-grained manganosite, with only minor hausmannite and carbonate. Coarsely crystalline carbonate is replacing the ore along fissures. This opens the possibility that much manganosite has been mislabelled "hausmannite" in Japan.
Gumma: Deep green, opaque masses to 2cm at the Kurokawa mine, with reddish pink rhodonite and grey tephroite. Similarly at the Hagidaira mine and Mogurazawa mine. Because the deep green color changes to black on exposure to air, local collectors attempt to preserve it with lacquer, which helps only temporarily; embedding in plastic is the only permanent solution.
Iwate: Abundant ore mineral in low-silica parts of folded metamorphosed Mesozoic sedimentary manganese ore at the Noda-Tamagawa mine. Anhedral grains to a few mm size, aggregated with a little tephroite and galaxite, formed a large mass in hausmannnite-rhodochrosite ore. Also as anhedral grains smaller than 1mm, disseminated in hausmannite-rhodochrosite ore and pyrochroite ore.
Nagano: As dark emerald-green vitreous, equant anhedral grains to 0.5mm at the Hamayokokawa mine, where it constituted one of the important ore minerals, abundantly disseminated in high-grade, banded and folded silica-poor hausmannite-alleghanyite ore in meta-chert country rock, with jacobsite, feitknechtite and rhodochrosite. Also as aggregates of tiny anhedral crystals surrounded by pyrochroite in rhodochrosite-alleghanyite ore. Black on the surface of old specimens. Rare tiny but perfectly developed terminated crystals here are the only japanese manganosites that appear to be relatively stable, keeping their green color even without protection from oxidation. Manganosite is also reported from the Yokokawa mine ((same place??)).
Shiga: In hausmannite-"manganosite"-rhodochrosite ore at the Ioi mine, there are a few irregular xls of manganosite, but most has altered to hausmannite. Also as a major component of rhodochrosite-sonolite-manganosite ore. As inclusions, always surrounded by a rim of hausmannite and/or "pyrolusite", in rhodochrosite in alleghanyite-galaxite-hausmannite ore.
MANGANOTANTALITE (mangan-tantaru-seki)
Fukuoka: Crystals occured in lepidolite-rich pegmatite in biotite granite at Nagatare. (Manganocolumbite and ferrotantalite also found at this locality.)
Ibaragi: Reddish crystals to 2mm in lithia-pegmatite intruding diorite at Myouken-san. (Ferrotantalite also occurs here.)
MANGANPYROSMALITE (mangan-pairosumaraito)
Shiga: Reported as "pyrosmalite" from the Ioi mine, probably really Fe-rich manganpyrosmalite.
Tochigi: Orange-red, hexagonal tabular to platy-prismatic crystals to 7mm, showing (0001) and (1010) faces with cleavage on (0001), as aggregates replacing rhodonite and chert wall rock, in cavities in rhodonite ore at the Kyuurazawa mine, a Paleozoic stratiform metasedimentary manganese deposit. Manganpyrosmalite was the main ore mineral in some parts of the mine, especially the Ohtaki and Shinsanjin orebodies, with tephroite and manganoan fayalite. Analysis shows a cation composition (apfu) (Mn'' 6.12, Fe'' 1.38, Mg 0.29, Al 0.10) (Si 6.10)... (with 5.00 wt% Cl, 0.17% SO3); D 3.12, H 4.5, RI 1.631-1.667. Other associated minerals include spessartine, manganogrunerite, manganoan tremolite, rhodochrosite, quartz crystals, pyrrhotite, sphalerite and chalcopyrite. A much more iron-rich manganpyrosmalite also occurs in the Ohtaki and Shinsanjin orebodies, and for a long time this was assumed to be true "pyrosmalite", although analysis shows not quite enough Fe to be that species and real pyrosmalite has not been confirmed: (Mn'' 4.07, Fe'' 3.50, Mg 0.43, Zn 0.005) (Si 5.83, Fe''' 0.14, Al 0.02, Ti 0.01) apfu... (with 5.63 wt% Cl, 0.02% P2O5). It appears as grey, pale green to blackish green or brown cleavages with pearly luster, with dark central zones, abundantly in ores with manganoan fayalite and rhodonite, and minor sulfides; RI 1.671-1.639. (Both analyses by H. Haramura, 1961). Similarly reported as "pyrosmalite" from the Takanosu mine and the Kamikuga mine.
MANJIROITE (manjiroh-koh)
Iwate: The type locality for this Na-dominant member of the cryptomelane group is the Kohare mine, where it occurs as dark brownish grey to black, dull or earthy, compact masses and crusts to 10cm, and as 2.5cm pseudomorphs, together with pyrolusite, nsutite, birnessite, cryptomelane and goethite, in the oxidized zone of bedded rhodonite-tephroite-rhodochrosite ore. Also in stalactitic habits to 2cm in length, with hundreds of such parallel stalactites grouped in "drippy-looking" crusts. Analysis shows (oxide wt%) Mn'''' 85.79, Mn'' 3.18, Fe''' 0.40, Al 0.62, Cu'' 0.03, Zn 0.03, Mg 0.18, Ca 0.22, Ba 0.16, Na 2.99, K 1.39, Si 0.12, and water 3.92, no Co or Ti. (D 4.29; streak brownish black; yellowish grey-white by ore microscopy.) Also at the Kawai mine, the Kotamagawa mine, the Tachikawa mine, and the Takinosawa mine (most of them in this same district).
MARCASITE (haku-tekkoh)
Fukushima: At the Akabane mine, marcasite forms botryoidal aggregates of twinned pyramidal crystals to a few mm diameter in cavities in massive chalcopyrite-sphalerite-pyrite ore in an epithermal quartz vein. Spear-shaped crystals formed of basal faces combined with macropinacoids, twinned on the unit prism, at Makugawa. ((same place??))
Ibaragi: Obara (mistake for Miyagi??????)
Iwate: The main ore mineral at the large Matsuo "pyrite" mine. With sulfur and pyrite as impregnation and replacement in Pleistocene andesite and tuff. Largest ore bed measured 1km x 800m x 80m.
Miyagi: Obara. (mistake for Ibaragi?????)
Nagano: Rounded grains of radial interior structure, 5 to 25mm diameter, near Nagano city. Greenish yellow on fresh fracture, but with brownish exterior. (Environment???)
MARGARITE (shinju-unmo)
Ehime: Margarite partially replaces kyanite (qv) porphyroblasts in amphibolite at Tohnaru. In metagabbro on Irazuyama.
Ibaragi: Whitish grey pearly scales to a few mm with calcite, dravite, zoisite and chlorite at the Hase mine.
Ouita: In the Shinkiura mine (Kiura emery mine), margarite forms the selvage zone, up to 1cm thick, bordering 4cm-thick fine-grained black emery veins (coundum, spinel, magnetite). Individual pearly margarite flakes reach 5mm.
MARIALITE (soh-chuu-seki)
Nagano: At the Kobushi mine, abundant as parallel aggregates of white prisms to 2cm. Even more abundant nearby at Kawahage, as whitish crystals to 2.5cm in cavities in a grey marble as product of contact metamorphism.
MARSTURITE (mahsuchuu-seki)
Gifu: Tsurumaki mine.
Tokyo: Deep to light yellow marsturite is found at the Shiromaru manganese mine as micaceous lamellae to 0.1mm, embedded in white rock (quartz or feldspar??).
MARUMOITE (marumo-koh)
Aomori: The kuroko-type ores of the Okoppe mine were the second world locality for this lead grey, metallic sulfosalt, Pb 32 As 40 S 92. (Shimizu, M., Ishizaki, Y., Honma, T., Matsubara, S., Miyawaki, R. (2005) Dufrenoysite and marumoite from the Okoppe mine, Japan. 8th Biennial SGA Meeting, Beijing, August 18-21, 2005, poster #100.)
MASKELYNITE (masukerin-chohseki)
Kagoshima: A shower of veined L6 chondrites known as the Kyushu meteorite shower fell over Satsuma and Osumi provinces on 26 October 1886; 44 Kg were recovered, containing forsterite, and abundant maskelynite grains with inclusions of recrystallized chromite.
MASSICOT (kin-mitsuda)
Kagoshima: The "lead oxide" being deposited at temperatures between 180 -340 C on volcanic rubble in fumaroles in the crater of Iwo-dake on Satsuma-Iwojima is probably massicot.
MASUTOMILITE (masutomi-unmo)
Gifu: Masutomilite crystals, zoned with zinnwaldite, occurs in pegmatite at Tawara, associated with cassiterite, topaz, schorl, albite and quartz, and at Naegi.
Shiga: The type locality for this K-Li-Mn-Al member of the mica group is Kunimi-dake at Tanokamiyama, where it occurs as transparent pearly, pale violet to light purple-violet, hexagonal platy crystals to 8cm across and 1cm thick in cavities in granite pegmatite, associated with quartz, albite, topaz and schorl. Crystals are always zoned, with a core of masutomilite surrounded by an outer zone of manganoan zinnwaldite. (Reported as colorless from the Nakasawa pocket here (probably just thin lamellae).)
MATILDITE (machiruda-koh)
Hyougo: Occasional rich specimens with petrukite- and sakuraiite-bearing stannite in a banded black sphalerite-chalcopyrite-bearing quartz vein in the Au-Ag ore polymetallic zone of the Ikuno mine. A selenian matildite also occurs in this zone, analysis corresponding to Ag 1.00 Bi 1.00 (S 1.78, Se 0.22), with selenian benjaminite (Shimizu, M. (1998) Resource Geology 48, 2, 117-124).
Tochigi: Blackish grey to black, selenium-bearing matildite impregnates a quartz vein in volcanic rock at the Nishizawa gold-silver mine, as thin wavy ginguro bands. Specimens from here have long been famous among Japanese collectors and can still be collected on an abandoned ore pile. No crystals. Associated commonly with tiny gold flakes, less often with pyrargyrite, realgar, and sometimes brighter grey roquesite.
MATSUBARAITE (matsubara-seki)
Niigata: This new Sr-Ti analogue of the silicates perrierite and rengeite is found in the riverbed of Suihodo, Kotaki-gawa, its type locality, in pale lavender-colored jadeite boulders derived from serpentinite melange in the high-pressure Renge metamorphic belt, which was created by a subduction zone. Matsubaraite is transparent grey with a bluish tint, or brown, and highly adamantine luster. Forms euhedral slender prismatic crystals to 0.5mm long, sometimes as hollow crystals or fan-shaped aggregates, within natrolite aggregates which are interstitial fillings between subhedral, pale violet, titanian jadeite crystals. Other associated species are lamprophyllite, tausonite, titanite, pink zircon and rengeite. Matsubaraite is brittle, has a white streak, hardness 5.5, density 4.13, no cleavage, no pleochroism, and no fluorescence under UV light.
MAUCHERITE (mauheru-koh)
Niigata: In Itoigawa city (perhaps with heazlewoodite and shandite in the eckermannite jade?).
Yamaguchi: At the Fukumaki mine and at Ube (same locality???).
MAWSONITE (mohsun-koh)
Hyougo: Orange-brown, bright metallic cm-size masses at the Akenobe mine, associated with brownish bronze stannoidite, cassiterite and wolframite. Metallic orange-brown masses in massive bornite from the Hyotan pit of the Tada mine. Also from the Ikuno mine.
Kyoto: Fukoku mine.
Okayama: Konjoh mine.
Shimane: Associated with stannoidite, bornite and chalcopyrite in garnet-wollastonite skarn in the lower part of the Maruyama Au-Cu-Pb-Zn-W orebody at the Tsumo mine.
Tochigi: Ashio mine.
MCALPINEITE (makkuarupain-ishi)
Wakayama: Centimeter-size crystalline crusts in Iwade-cho ((probably YamasakiÉ mine)).
MCGUINESSITE (makkuginesu-seki; makuginesu-seki)
Aichi: At the Nakauri mine, where local collectors sometimes confuse it with the more abundant nakauriite, but the mcguinessite has a more greenish blue color.
Saitama: Light blue-green, in serpentinized peridotite at Kamikawa town.
MELANTERITE (ryokuban; pisanite (cuprian) = doh-ryokuban)
Aichi: Spectacular museum-size, green crystals from the Iname sericite mine.
Akita: At the Ani mine. Both green ordinary melanterite and blue cuprian "pisanite" are found at the Osarizawa mine.
Okayama: Gemmy green, equant crystals containing minor Mg, Zn, Cu, at the Yanahara mine. The blue, more highly cuprian variety "pisanite" also occurs here.
Shiga: The copper-rich variety "pisanite" occurs at Kohzubata.
Shizuoka: Copper-rich blue "pisanite" at the Kune mine.
MELONITE (meronesu-koh)
Fukuoka: The Yokozuru mine was the first locality in Japan for melonite. Associated with volynskite, hessite and petzite as late-stage vein deposit in a scheelite-bearing quartz skarn.
Okayama: Visible in polished section as reddish brown specks with altaite, hessite, a Bi-telluride and a Ag-Ni-telluride in skarn at the Mihara mine, the 2nd japanese locality for melonite.
MENDOZITE (mendohsa-seki)
Shimane: Izumo (poorly described material).
Tottori: (Where???)
MERCURY (shizen-suigin)
Hokkaido: Native mercury was a major ore mineral at the Itomuka mine, as drops ranging from minute up to 1mm in 2-3mm vugs in cinnabar-impregnated massive milky quartz veins cutting altered vuggy Miocene andesite tuff containing heulandite, calcite, barite and pyrite. Also as tiny droplets associated with cinnabar in white epithermal quartz vein at the Shamani mine.
Miyazaki: Very small droplets in limonitic brownish loamy soil at Minato. The metallic mercury is easily separable from the earthy matrix.
Nagasaki: In porous Tertiary sandstone at Hirado. Similarly at Ainoura, where it was discovered around 1830 and exploited by Lord Matsuura.
Okayama: Minute drops with thin films of cinnabar in pyrophyllite in altered andesite at Fujino. With cinnabar at the Wake mercury mine.
MESOLITE (chuu-fusseki)
Niigata: The "high Na-mesolite" reported from Waniguchi is now classified as gonnardite (qv).
Yamagata or Aichi???: Mesolite crystals, displaying {110} and {111} faces, at Atsumi (Am. Min. 73, 613-618).
METASWITZERITE (meta-suuitsaa-seki)
Saitama: In manganese ore at the Hirogawara mine (and on Chichibu-Shiura Mt.?).
METATORBERNITE (meta-rindoh-uran-seki)
Fukushima: In Okuma-mura (Hata, S., and Iimori T. (1938) Tokyo Inst. Phys. Chem. Research Bulletin, 17, 355-358).
(See also under "Torbernite". Metatorbernite occurs at all the same localities.)
METAVIVIANITE (meta-ran-tekkoh)
Hyougo: Abundant as an alteration of, and pseudomorphs after, vivianite crystals in vivianite nodules to 3cm diameter in upper Pliocene clay exposed in Seishin-Chuhou roadcut at Oshibedani in Kobe city. Nodules are often thickly encrusted with limonitic santabarbarite and iron oxyhydroxides. Also admixed with vivianite. Similarly at other nearby localities for vivianite nodules.
Mie: Alteration of vivianite nodules in freshwater lacustrine sediments at Tarusaka.
METAVOLTINE (meta-boruta-seki)
Hokkaido: With voltaite and coquimbite in the Kohnomai gold mine.
Kagoshima: Bright orange, minute scaly crystals form mm-size aggregates associated with voltaite xls in white fibrous sulfate masses around a fumarole on Akuseki island. Also in the Hishikari gold mine.
METAZEUNERITE (meta-hidoh-uran-seki)
Okayama: Light bluish green, square scales on limonite-stained fracture surfaces at the Miyoshi mine.
(Also at all the localities listed for "Zeunerite" -qv.)
METHANE HYDRATE (not yet formally described as a mineral species)
Extensive fields of methane hydrate (clathrate) beds lie offshore in a roughly east-west belt stretching from Miyazaki-ken to western Shizuoka-ken. Also a small field southeast of Choushi, Chiba-ken. Large fields scattered around the south, west, and northeast coasts of Hokkaido, and off western Aomori-ken.
MIARGYRITE (miajiru-koh)
Kagoshima: Isolated lustrous complex crystals on drusy quartz at the Toyoshiro mine. Tentatively identified by ore microscopy at the Yunagano mine, but needs confirmation. Also from the Hojyo mine.
Miyazaki: Anhedral grains to 0.1mm, associated with pyrargyrite and tetrahedrite at the Ouchi Ag-Sb mine. The miargyrite is recognizable by ore microscopy by its greyish white color with red internal reflections.
Ouita: Massive aggregates of granular xls with poorly-developed faces, are associated with pyrargyrite in cavities and fractures in epithermal quartz vein at the Bajou gold-silver mine. With gold at the Mitsui-Ohtaka mine. Also in veins in native arsenic-stibnite-bearing andesite at the Mukuno Ag-Au mine.
MICROCLINE (bisha-chohseki)
(Some pegmatitic or miarolytic "microclines" from Japan are technically orthoclase, but labelled "microcline" merely on the basis of tradition and geological convenience.)
Fukushima: Short columnar microcline crystals, and Carlsbad twins, are found in the Ishikawa district in cavities in granite pegmatites, where feldspar has long been mined for the ceramic industry. Crystals as long as 1 m are known. Crystals up to 40 cm in large vugs at Wagu. The Suishoyama pegmatite worked a perthitic microcline pegmatite body shaped like a vertical pipe, 60m diameter, with much of the feldspar colored red by radioactive minerals.
Gifu: In the Naegi district, square prismatic xls to 6cm long occur in granite pegmatite vugs. Most exhibit Carlsbad or Baveno twinning. White opaque prisms to 17cm, usually exhibiting Baveno twinning, in pegmatites or miarolytic cavities in biotite granite at Tawara, associated with smoky quartz, albite, topaz, chlorite, hyalite opal and zeolites. (Some of this "microcline" = orthoclase.) Quarries in this district were still active until recently and produced a constant supply of specimens.
Iwate: In an unusual pegmatitic rock at the Noda-tamagawa mine, on the boundary between massive tephroite-rhodonite-braunite-hausmannite ore and a manganoan phlogopite-richterite-manganoan augite("urbanite")-bearing hornfels. The "pegmatite" consists of rhodonite, quartz, microcline, aegirine, alkali-amphibole and yoshimuraite. "Barian K-feldspar" here consists of intergrowths of barian microcline, hyalophane and albite.
Kagawa: Short prismatic xls and Carlsbad twins are associated with albite and smoky quartz in pegmatite cavities on Shoudoshima island.
Nagano: Light green "amazonite" xls in simple habits occur at Tadachi in granite pegmatite vugs. Short columnar Baveno twins in pegmatite at Moraiyama.
Shiga: At Tanokamiyama, columnar Baveno twins, Carlsbad twins, and more complex single xls, are associated with albite and smoky quartz in granite pegmatite cavities. (Some of this material = orthoclase.)
Yamanashi: At the Otome mine, creamy white simple xls are found in pegmatite vugs at Otomezaka; and columnar xls and Baveno twins with smoky quartz at Kurasawa.
MIHARAITE (mihara-koh)
Okayama: The type locality of miharaite, a rare Cu-Fe-Pb-Bi sulfide, is the Honpi deposit at the Mihara mine, where it forms microscopic intergrowths with chalcopyrite and galena, occasionally also wittichenite (from which it is indistinguishable by ore microscopy), as grains to a few hundredths of a mm across as inclusions in bornite grains in a bornite-rich skarn. Only visible in polished section, where it displays a pale grey to greyish white color. Also found at the Imooka mine.
MIKASAITE (mikasa-seki)
Hokkaido: The type locality for this anhydrous(?) ferric sulphate, the iron analogue of millosevichite, is near the Pombetsu river at Ikushunbetsu, in Mikasa city (whence the name), where it was discovered in 1994. Forms dull white to light brown, soft (H 2), porous, earthy aggregates to 10 cm of hollow spherical "crystallites" averaging 0.1mm diameter, as sublimates from high-temperature gas (307 C) in fissures over burning coal. Fe is partially replaced by Al and traces of manganese. (The water found in the original analysis was assumed to be non-essential and was discounted, but this left an incompatible Gladstone-Dale relationship between specific gravity and refractive index.)
MILARITE (mirah-seki)
Gifu: Very rare crystals in pegmatite at Hirukawa. Only about 4 specimens have been found.
Iwate: Sakihama.
Kyoto: Hatano.
MILLERITE (shin-nikkeru-koh)
Ouita: Radiating millerite sprays to 3mm long occur in fissures and embedded in a vein of green-stained opal and chalcedony at the Wakayama mine, in a serpentine dike cutting metamorphosed sandstone, shale and chert of the Chichibu metamorphic belt.
MIMETITE (mimetto-koh)
Gifu: Aesthetic yellow sprays of mimetite xls to 5 mm long (generally 1mm) in vuggy black matrix at the Horado mine.
Hokkaido: In the Otaru-Matsukura barite mine. (NB: Pyromorphite also occurs here.)
Miyazaki-ken: Gemmy transparent lemon yellow, short prismatic mimetite crystals to 2mm, with bi-pyramidal terminations, in the vuggy oxide zone of the Mitate Sn-Ag-Cu mine, associated with adamite. Also at the Toroku mine.
Ouita: Yellow, 1mm spherules scattered on green secondary copper minerals in vuggy gossan at the Kiura mine.
MINAMIITE (minami-seki)
Gumma: The type locality for this Na-dominant member of the alunite group is Okumanza, where it occurs around hot springs, associated with quartz, opal, sulfur, pyrite, rutile, woodhouseite and REE-bearing crandallite in a sulfurically altered 2-pyroxene andesite near the active volcano Kusatsu-Shirane. Minamiite forms pseudohexagonal crystals, up to 3mm diameter and 0.5mm thick (although they are normally micro-scaly and less than 0.3mm diameter), white to colorless with vitreous luster and a perfect cleavage. Individual crystals are intimately zoned with natroalunite and huangite, which accounts for the original confusion about the true chemical formula of this species. Originally described as Ca-dominant, then almost discredited as a species because the true composition corresponds to a calcian natroalunite, but now accepted as a valid species (CNMMN 1992) because the c-axis is double the length of natroaluniteÕs. Crystals of these compound alunite-group species line fissures or form white massive aggregates, sometimes as pseudomorphs after plagioclase phenocrysts or simply replacing the andesite matrix. Reportedly also as crystals to 0.5mm at Manza.
Kagoshima: "Minamiite" reported from the Nansatsu area is actually close to the ideal Ca end-member huangite, rather than minamiite. (Type locality minamiite was originally wrongly defined as Ca-dominant.)
MITRIDATITE (mitoridato-seki)
Hyougo: As excellent crystals and earthy masses in small vugs in the center of 2cm vivianite nodules from an upper Pliocene clay bed exposed in a Seishin-Chuhou roadcut at Katada in Kobe city. Possibly some of the world's best mitridatite! Also as dull grass-green coatings on vivianite crystals.
Ibaragi: In the phosphate-rich pegmatite at Yukiiri.
MOLYBDENITE (ki-suien-koh)
Gifu: Possibly the worldÕs finest and sharpest molybdenite crystals were found at the Hirase mine, where well-developed, thick tabular hexagonal xls to 15cm (Masutomi Museum), edges beveled by pyramid faces, occured in a highly fractured pneumatolytic-pegmatitic milky quartz vein cutting biotite granite. The molybdenite crystals generally fell out of their fractured matrix as loose floaters. Less perfect, incomplete crystals to 20cm across are preserved at the Geological Survey Museum in Tsukuba. Also as subparallel rosette aggregates, and massive up to 50cm. As thin flaky xls in white massive quartz with ferberite (qv), cassiterite and scheelite from a pneumatolytic vein at the Ebisu mine. Very similarly in the pneumatolytic vein or greisen of the Ichiyanagi tungsten deposit. Partially replacing kamiokite at the Kamioka Pb-Zn-Ag mine, in quartz-molybdenite boxwork veinlets in granite porphyry between the Maruyama and Tochibora orebodies.
Iwate: A rare constituent of folded metamorphosed sedimentary Mn ore at the Noda-Tamagawa mine. Molybdenite was the ore mineral at the Ohkawame, in skarns and associated quartz veins, with minor scheelite (qv).
Kagoshima: The trigonal polytype MOLYBDENITE-3R is found on Satsuma-Ioujima as very thin free-standing folia more than 0.1mm across, deposited quite abundantly in the crater floor by very high temperature fumaroles. (This occurence is reportedly very rhenium-rich, so somewhat analogous to the Kamui-dake fumaroles on Etorofu island.). In the "pegmatitic" wolframite-tourmaline-Bi-Au-bearing quartz veins of the Miyanoura mine on Yakushima island.
Niigata: Flat hexagonal plates to 10cm(!), sometimes beveled by pyramid faces, in milky quartz at Kawachi. (These were described by Wada (1904), but might have been really from the nearby Hirase deposit across the border in Gifu (qv).)
Shimane: At the Kakeya mine, massive aggregates of thin flaky xls occur in quartz from a pneumatolytic molybdenum deposit. Platy or lamellar, with no crystals, at Tamatsukuri. As lamellar embedded crystals to 2.5cm in the Komaki Mo-W-kaolin mine. Also at the Seikyuu mine, and the Yamasa mine.
Shizuoka: An iron-bearing molybdenite, "femolite", probably a mixture of molybdenite and pyrite, is reported from the Kawazu mine.
Toyama: Masses up to 20cm across at the Kokurobe mine.
Yamanashi: At the Otome (Kurasawa) mine, foliated hexagonal platy xls to 5cm diameter were found in a pegmatitic quartz vein. Well-crystallized at the Komagatake mine, in yellow limonite-stained quartz veins cutting granite. In sulfide ore veins at the Suzukura Cu-Zn-Pb-As mine. Also at Tsuruze.
MONAZITE-(Ce) (monazu-ishi; monazu-seki)
Aichi: Good crystals from pegmatite on Suribachiyama.
Fukuoka: Granitic pegmatites at Daisen produce yellowish granular monazite crystals to 2mm, associated with tourmaline and andalusite. At Kotohge, green-black monazite is associated with uraninite in red feldspar and smoky quartz.
Fukushima: Yellowish brown to toffee brown, tabular or prismatic xls to 3.5cm, but usually less than 1cm, exhibiting large (100) faces, smaller (011), (111) and (101), commonly twinned on (100), occur sparsely in granite pegmatite lenses in biotite-hornblende granite of the Ishikawa district, associated with quartz, feldspar, biotite, columbite, ishikawaite, zircon and green xenotime. One analysis from this district gave (as wt% oxides) (La,Nd) 31.27, Ce 21.08, Th 11.08, U6+ 0.42, Y 3.53, Al 0.80, Fe''' 0.66, Ca 0.52, Mg 0.27, P 27.52, Si 2.98, water 0.56 (Shibata, Y. and Kimura, K. (1921) Chem. Soc. Japan Journ., 42, 957-964). Obviously a new analysis is needed here, with better REE separation, but it would seem possible that La-dominant monazites might exist in this district. At Shionohira as resinous brown, short prismatic crystals to 5mm, in black matrix. At Fusamata with iimorite-(Y) in quartz-microcline pegmatite. Also in pegmatite at the Uzumine feldspar mine, and with ilmenorutile at Teshirogi. In non-schistose rocks of the Abukuma metamorphic belt at Kanougami, with staurolite, sillimanite, almandite, corundum and hercynite.
Gifu: In Naegi district granite pegmatites. At the Ebisu mine. An accessory mineral in fine-grained metasedimentary Mn ore composed of hausmannite, carbonate, garnet and bementite at the Nagashima mine.
Ibaragi: Good crystals came from the Yamanoo pegmatite quarry.
Kyoto: Associated with kobeite-(Y) in altered microcline in pegmatite at Shiraishi.
Mie: At the Takehara mine pegmatite, as 2cm dull chocolate brown crystals embedded in very friable cream-white feldspar.
Nagano: Lustrous blocky crystals to 0.6mm at Ikura. Minute crystals, about 0.005 mm, as inclusions in rhodonite at the "X" mine, in metasedimentary Mn ore.
Shiga: Rare dark red, semi-transparent inclusions in transparent topaz crystals from Tanokamiyama are subhedral monazite crystals, with curved or poorly-developed faces, to 6mm.
MONAZITE-(La) (rantan-monazu-seki)
Fukushima: (See note under Monazite-(Ce).)
MONTICELLITE (monchiseru-seki)
Hiroshima: In skarn at Kushiro.
Hokkaido: A component of metasomatically altered dunite in the Iwanai-dake alpine-type peridotite mass.
Kanagawa: At Hohkizawa, monticellite occurs as short prismatic subhedral crystals, associated with vesuvianite, wollastonite and calcite, and late-stage tobermorite and plombierite, in a contact zone between tonalite and limestone.
MONTMORILLONITE (monmoriron-seki)
Niigata: An acid hydrous Al-silicate, with minor Mg, from the Kambara district, was described in 1930 as the clay species "KANBARAITE", although it is now thought to be a variety of montmorillonite. Yellow to blue aggregates of tiny hexagonal crystals as an alteration product in Tertiary rhyolite, turning white on exposure to air. (D 2.67-2.917; RI 1.5200-1.5148.). Also in Itoigawa.
Yamagata: Greyish white, finely banded sedimentary bentonite is mined underground(!) at the Tsukinuno mine. Also from Rokkaku, from Hasedoh, and from Mujinamori ((same places??? overlap????)).
MONTROSEITE (monrohzu-seki)
Gifu: Unuma. (A continuation of the same paragenesis across the river in Aichi-ken. See under Volborthite - Tsugao.)
MORDENITE (moruden-fusseki)
Iwate: At Arasawa (Arasawa-mura), white transparent mordenite fibres to 5cm long, sometimes in cotton-like aggregates, fill amygdules in rhyolite-liparite. Some specimens are the most beautiful mordenites in Japan, as hemispherical sprays of silky white hairs to 5cm long, associated with minor quartz crystals. Microfibrous silky mordenite also composes much of a laminated or thinly bedded brownish white rock formed from altered volcanich ash.
Kagoshima: With ginguro-type silver ore at the Tamanoyama mine. Small needles with dachiardite-Ca, heulandite and quartz in hydrothermal veins at the Onoyama gold mine. White to pink filiform crystals to 3mm, in reddish vesicular Pliocene hypabyssal rhyolite at Yoshida.
Kanagawa: In altered andesite around Yugawara hot springs, filling amygdules with silky compact massive mordenite. In the Ohyama-Isehara district, and elsewhere in the eastern Tanzawa mountains, an upper zone of Miocene tuffs and volcanosedimentary rock, especially layers of glassy pumice tuff or glassy breccia, are altered to mordenite. Also in the Tanzawa mountains, with stilbite, heulandite and quartz in the outermost alteration zone around a quartz diorite (above the yugawaralite-bearing laumontite-wairakite zone).
Miyagi: In the Katayama geothermal wells, Onikohbe, at depths of 140 meters, temperatures from 60 to 140 C, in altered Pliocene-Pleistocene andesitic and dacitic tuffs, above a laumontite-analcite-yugawaralite zone.
Niigata: Beautiful crystals are found with clinoptilolite, erionite, chalcedony and quartz in vugs in mid-Miocene basaltic and dacitic agglomerate overlying olivine pillow basalt along the seashore at Maze. As cottony fibrous aggregates, associated with dachiardite-Na, clinoptilolite, barite and sulphides, in veins in altered rhyolite at Tsugawa. Drilling into marine strata in the Niigata oil field found mordenite with clinoptilolite at temperatures from 41 to 49 C.
Shizuoka: Abundant as white fibrous tufts and filiform sprays to 1.5cm long in vugs, and as silky masses to 5cm, with calcite, celadonite, violet apophyllite, white chabazite and colorless heulandite, in altered volcanic agglomerates in cliffs and beach boulders around Shoubusawa and the neighboring Yanda coastal cliffs, both in Kawazu. Compact fibrous masses, surrounded by thick masses of blue-green celadonite, in agglomeratic andesite cliffs south of Shirahama (Shimoda city). Mordenite sprays are often embedded in solid calcite-filled vugs, but can be exposed with weak acids. Also at Toishinden, in veins cutting propylitized andesite. Also at Sotoura and Yazu.
Tokyo: On Chichijima island: at Miyanohama, associated with pale yellow heulandite in andesite amygdules; at Hatsuneura, with dachiardite, heulandite and chalcedony; similarly at Susaki.
Yamagata: In zeolitized tuff at Nagasawa.
San-In district: abundant at Maji (Which prefecture???).
N of Kanto (Which prefecture???): Motajuku district (similar to Kanagawa-ken's Tanzawa zone around quartz diorite intrusion).
MORIMOTOITE (morimoto-zakuro-ishi) (= IMA # 92-017)
Okayama: The type locality for this Ca-Ti-Fe-Si member of the garnet group is Fuka, where it occurs in one endoskarn boulder embedded in altered monzonite in a roadcut that has now been cemented over for erosion control. Black adamantine, euhedral or subhedral crystals to 1.5cm, sometimes surrounded by grossular-andradite rim. Associated with calcite, vesuvianite, grossular, wollastonite, hematite, prehnite, fluorapatite, perovskite, zircon, baddeleyite, calzirtite. (No cleavage; H 7.5; D=3.80, G=3.75; N=1.955) Related to andradite by the substitution Ti+Fe''=2Fe'''. Analysis shows (as wt% oxides) Ca 31.35 Mg 0.87 Mn 0.23, Ti 18.5 Fe'' 7.78 Zr 1.48, Si 26.9 Fe''' 11.4 Al 0.97. (NB: Some schorlomites might actually be morimotoites as presently defined, and the so-called "morimotoites" found by hopeful field collectors in the spurrite skarns of Fuka are "schorlomite" = Ti-rich andradite; Caveat emptor!)
MOTTRAMITE (mottoramu-seki)
Tochigi: As yellow-green "mold" on amethyst and palygorskite in rhyolite at the Manjyu epithermal gold-silver mine.
Yamaguchi: Hidaka mine; and at the Sokoku mine. Also at Munakuni (same as one of previous mines???).
MUSCOVITE (shiro-unmo)
Aichi: Fine-grained massive white "sericite-2M" (illite or muscovite?????), some with minor iron staining, is mined for cosmetic purposes (wavy optical effects in shampoo) at the Furikusa mine (previously known as the Iname mine).
Ehime: Ammonium-bearing muscovite is abundant in the Ohgidani clay mine, with tobelite.
Fukui: "Cerasite" as silvery white pseudomorphs after blocky cordierite xls to 2cm long, 9mm cross section, at Torihama, contrasting distinctly with the dark grey hornfels matrix.
Fukuoka: At Nagatare, muscovite forms plumose aggregates of pearly white lamellae, with quartz and orthoclase in a greisenized granite. In pegmatites at Kotohge, muscovite forms pseudomorphs after thick prismatic sekaninaite crystals to over 7cm, dark grey on c-face cleavage surfaces, brown on prism faces.
Gifu: Forms the silvery rims around large zinnwaldite crystals in the miarolytic pegmatites of Hirukawa village; druses of smaller crystals are generally all muscovite. Light green, talc-like muscovite forms a cm-thick alteration zone around light violet corundum crystals in graphite-biotite-rich rocks in Kawai-mura.
Kyouto: "Cerasite", commonly known in Japan as "sakura-ishi" (= "cherry blossom stone") because its color and cross-section resemble that flower, is a muscovite pseudomorph after trapiche cordierite sixlings occuring, sometimes abundantly, in hornfels, slate or their weathered elluvial soils. Greenish when broken out of fresh rock, but local collectors prefer the loose weathered ones which have oxidized to a silvery pinkish white color more reminiscent of their namesake cherry blossoms; to 8mm diameter at Kameoka-hachiman and nearby at Yunohana. In contact metamorphic slate at Sakuratenjin as hexagonal prisms to 15mm long and 8mm diameter, with the typical "cherry blossom" cross section. Also at Tamagawa.
Nagasaki: Barium-manganese-bearing muscovite occurs in pink piemontite schist containing lenses of braunite ore around the Matsugaseko mine. Also at the Tone mine.
Nara: Peculiar divergent or plumose rusty masses to 10cm on Bodai-yama. "Sericite" (muscovite?) at the Kambe mine and the Tohnomine mine.
Niigata: Green nickel-bearing muscovite is a major component of some greenish pebbles on Itoigawa beaches.
Okayama: "Sericite" is mined from an upper Cretaceous deposit at the Tsuchihashi mine.
Shiga: At Tanokamiyama, as pearly white, rough hexagonal tabular xls to 7cm across in granite pegmatite.
Tochigi: "Sericite" muscovite occurs as pseudomorphs after hexagonal "trapiche" cordierite crystals to 6mm (by hydration, not weathering) in hornfels in the Watarase riverbed near the Ashio mine. "Sericite" is also mixed with the pyrophyllite from the Nasu Roseki mine.
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