Encyclopedia of Japanese Minerals (Go to Intro Page)
by Alfredo Petrov
Minerals Starting with "D"
DACHIARDITE-Ca (kai-dakiarudi-fusseki)
Shizuoka: It has been suggested that some or all of the "epistilbite" reported from Toi, with yugawaralite and calcite in vugs in propylite, may actually be dachiardite because of some incompatibility between the conditions of formation of yugawaralite and epistilbite.
Tokyo: At Hatsuneura on Chichijima in the Ogasawara islands, along with calcian dachiardite-Na, where they form radiating aggregates of platy prismatic crystals in chalcedony veins transecting altered mafic pillow lava. Associated with mordenite. One analysis corresponds to (Ca 1.77, Na 1.24, K 0.49) (Al 4.80, Si 19.08) O 48 (H2O) 12.10 (Nishido and Otsuka, 1981).
DACHIARDITE-Na (sohda-dakiarudi-fusseki)
Niigata: Yanagi-shinden in the Tsugawa district is a co-type locality for this rare zeolite occuring as colorless to white or beige crusts of microacicular crystals in vugs in veins cutting altered Miocene rhyolite. Associated with mordenite, clinoptilolite, barite and sulphides. Analysis gave the formula (Na 2.93, K 0.36, Ca 0.16, Mg 0.01) (Al 4.37, Fe 0.06, Si 19.76) O 48 (H2O) 12.6 (Yoshimura and Wakabayashi, 1977).
Tokyo: Calcian dachiardite-Na is found with dachiardite-Ca at Hatsuneura in the Ogasawara islands (qv Dachiardite-Ca). On the same island, at Susaki, dachiardite-Na forms radiating fibrous aggregates with heulandite and mordenite in vesicular andesite pillow lava.
DANALITE (dehna-seki)
Hiroshima: Danalite of composition (danalite56 helvite28 genthelvite16) is associated with alkali-feldspar and deep violet fluorite in monzonite at the Mihara fluorite mine. Also in the Hirako mine (Vienna museum spec.).
DANBURITE (danburi-ishi; danburi-seki)
Miyazaki: Danburite from the Toroku sphalerite-chalcopyrite-galena mine is well-known in worldwide systematic collections, and was formed by pneumatolytic metasomatism in a contact deposit. Crystals are long prismatic, up to 3cm wide and 24cm(!) long, the prisms showing large (120) faces and very narrow (100) and (010) faces, terminated by large (041) and (101) faces, with c-faces being either very small or absent, and normally exhibit a small upper transparent colorless zone along with a lower translucent to almost opaque white, pale green or light greenish grey zone that is clouded by inclusions of white or pale greenish white micro-filiform tremolite. Rarely, most of the crystal is colorless, and the cloudy zone at the bottom is small. Although larger on average than the Obira mine crystals, the Toroku ones are not as sharp. Sometimes occurs with large ferroaxinite crystals; other associates include tourmaline, hedenbergite, andradite. Occasionally facetted as a gem. Also nearby at Yamaura and in the Mitate mine.
Ouita: Colorless transparent to subtransparent prismatic crystals to 9 cm long (but rarely over 4.5cm) and 2cm wide, formed by pneumatolytic metasomatism around the Obira mine, especially at Higashi-Shohdo. Originally thought to be topaz before Tsunashiro Wada correctly identified it. The (120) prism face is the most obvious but, unlike at the Toroku mine, a small but distinct c-face termination is present here, along with narrow (110) and (140) prism faces; the (041) face is well-developed but usually smaller than (120); and (101) is sometimes well-developed but not always. Terminations are either sharp narrow pyramidal ("sword-shaped"), or chisel-shaped, depending on the relative development of w and d faces. Prism faces are vertically striated; w faces are horizontally striated, with vertical grooves and other etch figures. Although generally smaller than the danburites from the Toroku mine, the Obira crystals are usually better formed. Associated with axinite, quartz, calcite, brown garnet, sphalerite and galena, in cavities in veins in marble. Crystals are covered with white crusts when first found, but these are easily removed. May contain inclusions of brown garnet dodecahedra to 0.5mm, and unidentified white globular inclusions. Analysis showed 14.47 wt% CaO and 7.67% MgO (a magnesian danburite?); density 3.09. Gemmy colorless 1mm double-terminated crystals have been found as rare inclusions in fluorite crystals here.
DATOLITE (datoh-seki)
Ehime: As pink equant xls to 2cm, and as light pink to purplish pink botryoidal forms, individual botryoids to 1.5cm, at the Makinokawa quarry, in cavities to 10cm wide in the lower zone of a biotite andesite dyke, with calcite xls, fluorapophyllite xls and spheroidal natrolite. Above this is a zone with stilbite, heulandite and mordenite, without datolite.
Fukushima: Botryoidal datolite occurs with thaumasite, wollastonite, etc., In skarn xenoliths derived by hydrothermal alteration of original high-temperature spurrite-gehlenite skarn xenoliths in andesite at Tadano.
Miyazaki: Oil-yellow, pale blue or colorless crystals to 9 x 6 cm(!) at Noborio, growing on older quartz and axinite crystals which sometimes penetrate the datolite or form inclusions in it; associated with green pyroxene, garnet, mica, epidote, calcite, galena. Some faces vitreous, some etched and duller, the x face being especially rough; horizontal striations on the m and sometimes also n faces. An analysis gave 0.38% MgO and 0.34% Fe2O3. Transparent white xls to 1cm occur on axinite xls at Yamaura in a contact metasomatosed deposit. Colorless crystals to 4.5cm(!) at the Iwato mine (Geological Survey specimen, Tsukuba). A new locality for excellent datolite crystals was discovered as recently as 2006 at Oshigahae. (All four of these localities are in or around the Toroku mine.)
Ouita: At the Obira cassiterite-sphalerite-chalcopyrite mine, as beautiful crystals in druses with axinite in skarn.
Shizuoka: At Nyushima in Umegashima, massive white datolite is associated with violet axinite crystals.
DAWSONITE (dohson-seki)
Gunma: Dawsonite forms radial aggregates of needles in veinlets in sandstone, associated with dolomite and minor pyrite, siderite and gibbsite, at Tatarazawa. Chromian dawsonite also occurs here, with chromian alumohydrocalcite in serpentinite.
Mie: Chromian dawsonite is associated with nordstrandite and chromian alumohydrocalcite in the crush zone in "black schist" in the Median Tectonic Line, Sana area. The 16.13% Cr oxide indicates that a quarter of the Al positions are occupied by Cr. Also as beautiful acicular sprays to 1mm at Nyu.
Osaka: Associated with alumohydrocalcite in Upper Cretaceous marine sediments in the lower part of the Izumi Group, in Kishiwada city. Pearly white stellate "suns", 2 to 4mm across, on fissure walls to 15cm across in mudstone nodules at Showaike.
DESAUTELSITE (desohterusu-seki)
Aichi: Orange crystals to 0.5mm form thin crusts spread over more than 1cm serpentine surfaces at the Yoshikawa nickel mine.
Mie: The best desautelsite in Japan (and among the best in the world?) was a find of flaky aggregates composed of crystals up to 2mm in the Shiraki serpentine quarry. Another desautelsite find was made about 15km further south, in Funakoshi, during the levelling of a serpentine outcrop for construction of the junior high school.
DIAOYUDAOITE ?? (diaoyuudao-ishi)
Okinawa: The type locality for this "mineral" was in seafloor sediments at 1,500m depth off the Senkaku islands as colorless to light green, transparent hexagonal flakes to 0.5mm, showing good cleavage, with microscopic inclusions of "native" chromium. Abundant in the semi-heavy fraction of the seafloor sediment, together with hornblende, epidote, dolomite, chlorite and biotite, supposedly derived from nearby basalt. Named after the Chinese name for these islands. However, it is unlikely that this is a true mineral. Perhaps illegally dumped industrial waste from chromium refining or corundum synthesis?
DIASPORE (daiasupoa)
Akita: In sphalerite-pyrite "kuroko"-type ore at the Hanaoka mine, a rather unexpected environment for diaspore.
Fukuoka: Lilac-colored diaspore at Sasaguri.
Hiroshima: Diaspore as creamy white to greyish granular crystals and cleavages to a few mm across, associated with massive pyrophyllite, alunite, kaolinite and sometimes massive bluish corundum, in a hydrothermal alteration pyrophyllite deposit at the Shoukouzan mine. The diaspore here is quite pure, containing only 1.37 wt% silica, 0.10% CaO (Yoshiki 1933; DHZ 5).
Iwate: A brecciated mixture of zunyite, diaspore and sericite derived from highly altered Miocene rhyolite constitutes the rock type "kochite" (after Kouchi-mura) in Ishidoriya-cho.
Niigata: A boulder on the seacoast of Ohmi town consisted mainly of massive violet diaspore, with subsidiary prehnite, chlorite and rare niigataite.
Okayama: Nodular balls to 7cm diameter composed of concentric layers of pyrophyllite and fine-grained diaspore, known locally as "medama-ishi" ("eyeball stones"), are found in kaolinite in a hydrothermal alteration pyrophyllite deposit at Mitsuishi. Similarly nearby at the Ou'hira mine, where cream-colored balls, in part stained ochre brown, exceptionally reach diameters of 30cm, but normally only 2.5cm.
DICKITE (dikkaito)
Hiroshima: Dickite, as compact creamy white masses, in part stained ochre yellow, is a minor component of a pyrophyllite deposit replacing dacitic tuff at Shohkohzan. Sometimes with embedded blue corundum (qv).
DIOPSIDE (toh-kiseki; "diallage" = ihaku-kiseki)
(NB: Most augites (qv), except "ferroaugite", are really just impure varieties of diopside and ought to be included here.)
Aichi: The variety "diallage" at Ubuzan.
Ehime: The "extremely low sodium" clinopyroxene from "normal eclogite" on Gongenyama (described in the omphacite section of DHZ) has the empirical formula (Ca 1.008, Na 0.006, K 0.002) (Mg 0.949, Fe'' 0.054, Fe''' 0.028, Ti 0.005, Mn 0.001) (Si 1.932, Al 0.044) O 6. The variety "diallage" occurs on tiny uninhabited Kajishima off the north coast of Ehime.
Fukushima: At Domeki in Furudono-machi ("Gozaisho-Takanuki district"), Fe-rich "salite" (Ca 0.964, Mg 0.564, Fe'' 0.313, Fe''' 0.077, Mn'' 0.027 apfu) occurs in amphibolite. The (Mg+Fe'')/Ca ratio in this area (central Abukuma plateau) increases with increasing grade of metamorphism, becoming augitic at higher grades. Some skarn xenoliths in andesite in a quarry at Tadano are composed of a wollastonite-grossular-diopside assemblage.
Gifu: Abundant green to blackish green or green-brown, transparent to translucent, thin prismatic diopside crystals can be found in an accessible tunnel at the Horado mine. Crystals up to 3cm x 1cm are common, but very rarely also up to 10cm x 1.5cm. On a micromount level, excellent sharp transparent brownish colorless crystals to 2mm. Green diopside occurs with brown grossular at the Kasuga mine.
Hokkaido: Chromian diopside forms a chromite-clinopyroxenite cumulate in Kamuikotan metamorphic rocks at the Tomiuchi mine, associated with secondary purple "kaemmererite".
Iwate: From the Kamaishi mine. The manganese-rich "schefferite" variety occurs at Sarukabeyama.
Kanagawa: Greenish grey aggregates of granular diopside crystals occur at Houkizawa, associated with granular garnet and small acicular xls of white natrolite in contact metasomatosed dolomite.
Mie: Secondary diopside occurs both in prismatic habits and as unusual fibrous radiating aggregates in serpentinized peridotites of the 6km x 500m Asama-gatake layered intrusion. The cation composition Ca:Mg:Fe varies from 49:46:5 to 40:47:13. Associated with chrysotile, chlorite, andradite (rarely titanian "melanite"), chromian magnetite (qv), actinolite and ilvaite (qv). Diopside is not normally common as a product of serpentinization, but has also been reported from elsewhere in the Mikabu greenstone belt. (Primary magmatic clinopyroxenes were largely replaced by actinolite.)
Nagano: Manganoan diopside ("schefferite") occurs with quartz, barite, albite, braunite, in rhodonite ore at the Hamayokogawa mine.
Niigata: Dark green anhedral grains in white pectolite-albite matrix in the Ohmi river.
Okayama: With andradite, xonotlite, wollastonite and quartz in skarn at the Sanpo quarry. Omphacite (qv) -diopside vein at Ohsayama.
Saitama: Greenish grey, euhedral short prismatic xls to a few mm occur in contact metasomatosed limestone, associated with grossular at the Chichibu mine. Also with clintonite, vesuvianite and hydroxylellestadite. Also at this mine, in Uzunosawa, Nakatsugawa, with apatite in vugs in contact metasomatosed magnetite ore. Also in the Nagatoro district, and in serpentine at Nishiwada.
Shizuoka: Isolated crystals of "salite" (Ca 0.881, Mg 0.825, Fe'' 0.131, Al 0.077, Fe''' 0.067, Ti 0.011, Mn'' 0.005 apfu) in hypersthene-bearing olivine-augite basaltic tuff on Taga volcano, Wadaki. On the same volcano, at Chojahagara, "salite" (Ca 0.895, Mg 0.849, Fe'' 0.153, Fe''' 0.077, Na 0.017, Al 0.009, Ti 0.007, K 0.006, Mn'' 0.001 apfu) occurs in olivine-augite basalt. In general, in the Izu-Hakone volcanic province, the earliest pyroxenes have diopsidic compositions, with increasing iron in those that crystallize later.
Yamaguchi: The manganese-rich "schefferite" variety occurs at the Kuga mine.
Yamanashi: At Kamisano, dark green, short prismatic xls to 4cm, often twinned, of chromium-bearing diopside are found as phenocrysts in a porphyry and as loose euhedral crystals weathered out. Widely distributed in Japanese collections. At Kozohri in Sano (same place??), green "chromian diopside" (Ca 1.011, Mg 0.873, Fe'' 0.062, Cr 0.016, Fe''' 0.01 apfu) in basalt. Also includes (wt% oxides) P 0.03, Ni 0.016, V 0.004.
DJURLEITE (dyurure-koh)
(Japan could be considered a co-type locality for djurleite, since it was independently described from several japanese localities in 1962, the same year it was described from Montana. All these occurences had been known previously but considered to be chalcocite, and it was named for the person who first synthesized the compound, before it was discovered in nature.)
Aichi: Grey-white masses of djurleite to 5cm, tarnished dark blue, occur in serpentinized gabbro at the Nakauri mine, associated with heazlewoodite, cobaltpentlandite, native copper, and secondary blue nakauriite. As veinlets between magnetite and green serpentine.
Akita: In the Osarizawa mine as pseudomorphs after cubic galena crystals (so-called "harrisite") to 2cm, showing dominant (100) and minor (111) faces, associated with pyrite, chalcopyrite and barite in drusy cavities in an epithermal quartz vein; also with covellite and osarizawaite. Previously erroneously thought to be chalcocite. Also at the Ani mine, associated with anilite (qv) in Fe-poor areas of the secondary enrichment zone. A few individual euhedral crystals of pure djurleite have been found on quartz here, but most are an intimate mixture of djurleite and anilite phases, and all the "anilite" crystals also contain djurleite. Also at the Hanaoka mine.
Shizuoka: Reported at the Kawazu mine. With green waxy nontronite in slickensides at Kamewari-tohge.
DMISTEINBERGITE (domisutainberugu-ishi)
Gumma: White pearly micaceous plates form veinlets with wairakite in a gabbro quarry in Katashina. This material is probably the world's best dmisteinbergite, and the first locality for the natural material, not created by a mine fire!
DOLOMITE (kukai-seki)
Gifu: Dolomite was mined from dolomite skarn at the Kasuga mine. Also in the Ibi district.
Ibaragi: Grey massive dolomite, showing only cleavage faces, forms veins in peridotite at Machiya. Also in Hitachi-Ohta city (same place??).
Iwate: Golf-ball-size spheres of whitish dolomite pseudomorphs after radiating, hexagonal prismatic aragonite trillings, with individual prisms to 7mm diameter, occur at the Iwasawa mine. Fine-grained dolomite marble at Kamineichi, with inclusions of kotoite and ludwigite. Also at Kebaraichi and at Nejoh.
Niigata: Pearly white, intergrown 1cm rhombs at the Iide lead-zinc mine. In Shibata city. (Probably same place.) Also at the Akatani mine.
Tochigi: At Minowa, a homogeneous grey dolostone is formed almost entirely of interlocking dolomite rhombohedra. Also at Kuzuu.
Wakayama: White to brownish white, thin lenticular 2mm crystals form wide druses, associated with colorless magnesite rhombs, in Yuasa-cho. Light blue translucent dolomite from a quarry in Wakayama is occasionally used to cut cabochons for gem collectors.
NB: Dolomite is rarely a minor constituent of the "genno-ishi" calcite (qv) pseudomorphs after ikaite found in several prefectures.
DONPEACORITE (donpiikoh-kiseki)
Hokkaido: Tatehira.
DRAVITE (kudo-denki-seki)
Ehime: At the Besshi mine and the Sazare mine.
Fukuoka: Short prismatic black crystals to about 1cm, with hexagonal cross-section, embedded in silvery brownish to greenish micaceous vermiculite rock in Maibaru city. (Romaji transliteration of exact locality= ???? Kanji signifies "No Water".)
Yamanashi: Quartz crystals in granite pegmatite at Takemori, occasionally doubly terminated, often contain abundant brown acicular dravite inclusions, sometimes also with minute scales of muscovite, spheroidal chlorite, and other minerals. Such specimens are known to Japanese collectors as "kusa-iri-suisyou" ("grass within quartz").
DUFRENOYSITE (dyufurenoi-koh)
Aomori: Black microacicular, included in colorless barite at the Okoppe mine. Also as 1mm free-standing needles between thin tabular barite crystals. Not distinguishable from the baumhauerite here without XRD.
DUMORTIERITE (dyumoruchi-seki)
Miyazaki: Short prismatic crystals, up to 0.5 x 0.1mm, with remarkably strong pleochroism (deep blue; red-violet; colorless), are abundant with quartz, K-feldspar, albite and biotite in granite porphyry, 2km south of Kobutokoro, near the Matsuo mine.
Nagasaki: Microcrystalline violet masses from Ohtohzan at the Gotoh pyrophyllite mine are often beautiful enough that they have a market as decorative rock.
Nara: As mm-size grains disseminated in an unusual granite porphyry along the Misen river, associated with ominellite (qv), sekaninaite, andalusite and topaz.
Niigata: Light cobalt-blue veins in white river cobbles in Itoigawa.
Tochigi: Intimately associated with pyrophyllite, sericite and quartz in a highly acid-altered argillic halo along a fracture zone in Neogene quartz porphyry at the Nasu Roseki mine and elsewhere in Kuroiso city. Also at Momomura (Momura?) as rich bluish aggregates in greyish quartz.
Yamanashi: Pale violet dumortierite occurs with quartz and magnesiofoitite at Kyonosawa, in andesite and dacite which were highly altered by acid hot springs in a fissure zone. Also in Nishizawa (same place?).
DYPINGITE (daipingu-seki)
Aichi: From the Yoshikawa mine, from where previously described as "YOSHIKAWAITE", a supposedly "higher hydrate of hydromagnesite", to which it decomposes at 150 degrees C. It can be found as white botryoidal crusts as a spring water deposit on serpentine under dangerous overhangs in the open pit. (Analysis showed 7.76H2O pfu, rather than the theoretical 5 of dypingite.)
DZHALINDITE (jahrinda-seki)
Shizuoka: Yellow or colorless, pyramidal crystals to 0.1mm, composed of much smaller trigon units in parallel growth, in cavities at the Kawazu mine. Some samples are close to end-member composition; others have considerable ferric iron replacing indium. Formed by oxidation of roquesite.
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