Encyclopedia of Japanese Minerals (Go to Intro Page)
by Alfredo Petrov
Minerals Starting with "Z"
ZALESIITE (zareshi-seki)
Hiroshima: Pale green transparent needles to 0.5mm, with bluish tint and adamantine luster, as sprays and microtufts in fractures of friable tan-colored rock at the Setoda copper-tungsten deposit (now a granite quarry) on Ikuchi island. Sometimes labelled with the obsolete name "Agardite-(Ca)". Some are also surprisingly rich in cerium, as opposed to the Y and La that are more prevalent in other agardites.
ZARATITE (zarate-seki)
Ouita: Reported from the Notsuharu mine and the Wakayama mine - Needs reconfirmation.
ZAVARITSKITE (zabaritsukii-seki)
Gifu: As a dark grey or blackish, greasy-submetallic alteration crust surrounding masses to 6mm of native bismuth, and itself surrounded by greyish yellow earthy koechlinite, in pneumatolytic wolframite-bearing white quartz veins at the Ebisu and Tohgane (Takane) mines.
ZEOPHYLLITE (zeofiru-seki)
Okayama: Zeophyllite is associated with cuspidine and natroapophyllite in a white skarn which was altered by fluorine-rich fluids, in the Sanpo quarry.
ZHANGHENGITE ? (qv "BRASS")
ZINC (shizen-aen)
Tokyo: There is a reliable but unpublished report of native zinc as inclusions in at least one of the famous Miyake island anorthite (qv) crystals, presumably of the same origin as the more common copper and "brass" microfilm inclusions there.
ZINNWALDITE (chinwarudo-unmo)
(Some of the material listed under "Protolithionite" is probably zinnwaldite.)
Gifu: Zinnwaldite occurs as good crystals zoned with muscovite (silvery rims) or masutomilite (violet) in granite pegmatites or miarolytic cavities in coarse-grained biotite granite at Tawara, associated with cassiterite, topaz, schorl, albite and smoky quartz. Similarly also elsewhere in the Naegi district. Analysis of a zinnwaldite from a pegmatite in Naegi town corresponds to (K 1.818, Ca 0.182, Na 0.138) (Al 1.73, Li 1.58, Fe'' 1.13, Fe''' 0.49, Mn'' 0.21, Mg 0.08, Ti 0.01) (Si 5.80, Al 2.20) O 19.6 (OH 2.92, F 1.81) (Z. Harada, 1954; in DHZ).
Ibaragi: "Lithian biotite" at the Takatori mine = zinnwaldite?
Okayama: Takazawa mine. "Li micas" (zinnwaldite? lepidolite?) at Minagi.
Shiga: At Tanokamiyama, zinnwaldite forms pearly white to grey, thick tabular hexagonal crystals to 12cm across, associated with smoky quartz and microcline in cavities in granite pegmatite. Sometimes pale brown zinnwaldite is zoned with pale violet masutomilite, associated with albite, topaz and schorl.
ZIRCON (jirukon)
Ehime: "HAGATALITE" is an obsolete name for very REE-rich zircon from Hagata and Mategata, described in 1925, associated with fergusonite-(Y) and allanite in pegmatitic biotite. Yellowish grey, brownish grey or grey crystals from 1 to 5mm, either short prisms displaying p(111) and a(100) faces, or pyramidal with p(111) and small m(110). Analysis (as oxide wt%) Zr 42.0, Si 29.7, REE 13.1, Al 2.8, (Nb,Ta) 2.7, Fe''' 2.3, Th 1.5, Ca 0.3, Mg 0.2, U tr, volatiles 5.5. (Grey or dark grey streak; H 7.5: D 4.4.) "OYAMALITE" is an obsolete name for REE-phosphate-rich zircon from Ohyama, described in 1925, dark green or brown on fresh fracture, but pale brown on exposed surface. Analysis (as wt% oxides): Zr 40.9, Si 25.7, REE 17.7, P 7.6, Al 2.0, Th 0.6, Mg 0.8, Ca 0.6, Fe''' 0.6, volatiles 3.5. Only 2 specimens were collected, a 2mm crystal and a 7mm radial agggregate, from pegmatitic feldspar. (Streak yellowish white to white; H 7.5; D 4.1.) "Oyamalite" also occurs with fergusonite at Moriage and Mategata. Zircon occurs in the aegirine-syenite on Iwagi island.
Fukushima: With quartz, feldspar, biotite, monazite-(Ce) and ishikawaite in granite pegmatites in biotite-hornblende granite in the Ishikawa district, sometimes in parallel or epitactic growth with green xenotime. A very yttrium-rich zircon (over 10% Y oxide by weight), which also has about a tenth of the formula silicate replaced by phosphate, occurs in pegmatite with allanite, fergusonite and thorogummite at Hayamadake. The material known as "NOGIZAWALITE" from Nogizawa-mura is supposedly a mixture of zircon and the inadequately described mineral "AWAZULITE" (qv). With ilmenorutile and garnet in pegmatite at Teshirogi. Also from Fusamata and from Suishohyama.
Gifu: Crude alluvial zircon crystals, anhedral grains and spheroidal aggregates from 1mm to 1cm, of resinous luster, greenish grey, dark pistacio-green, grey or brown color, often reddish brown at the terminations, occur in a commercial cassiterite placer deposit, derived from granite pegmatites, near Takayama in the Naegi district (whence the old name "NAEGITE"). Dull, rough p(111), a(100) and m(110) faces are sometimes recognizable in rare single crystals to 7mm, with prismatic, thick tabular, or pseudododecahedral habits, but most are very crude. Associated with much more abundant fergusonite. "Naegite" was originally incorrectly described as a new U-Th-silicate, the Zr having been overlooked, but is really a Y-U-Th-bearing zircon, almost always thoroughly metamict, with a low specific gravity of 4.09; H 7.5. Analysis shows the following elements (expressed as weight % of oxides): Zr 48.7, Hf 3.5, U 2.5, (Nb,Ta) 2.5, REE 6.1, Th 2.9, plus minor Fe and 2.7% water; another gave Th 5.01, (Nb,Ta) 7.69, UO3 3.03, Y 9.12. The Nb-Ta may be present as submicroscopic inclusions rather than as part of the zircon itself. Zircons from granites in Hirukawa show very variable contents of radioactive elements, ranging from none up to 3.5 U and 2.5 Th (oxide wt%).
Ibaragi: At Myohken-san, as euhedral brown crystals to 2mm, in pegmatite with elbaite and beryl. Also in the Yamanoo pegmatite quarry.
Kagawa: In the Setouchi acid volcanics in Takamatsu. In pegmatite with smoky quartz on Shohdo island (the silica mine at the NW end of the island?).
Kyoto: Crude rough reddish brown crystals to 2.5cm in rare earth pegmatite at Ohro. Also at Ohmiya.
Nagano: "YAMAGUCHILITE" is the obsolete name for a very REE-rich and phosphate-bearing, low density metamict zircon described in 1936 from Yamaguchi-mura (on the Nagano-Gifu border, not far from the SE Gifu-ken pegmatite districts). It contains (expressed as wt% of oxides): Zr 40.2, Hf 3.4, REE 15.89, Th 3.52, U 2.08, Ca 1.23, Fe''' 0.59, Mn'' 0.50, Al 0.48, Mg 0.03, Si 21.35, P 4.23, C 0.61, and 0.54 Na-Ta-Sn-Pb. Occurs in pegmatites and graphic granite as granular spheroidal masses or radial aggregates composed of brown to dark brown poorly-developed crystals generally less than 5mm, but up to a max. of 4.5cm. Uncommon individual tetragonal crystals showing p(111) and a(100) faces. (H 6; D 3.971; RI approx. 1.7; streak pale brown.)
Nara: Tiny euhedral crystals are found with almandite and sapphire in alluvium at Anamushi.
Niigata: Fluorescent zircon occurs in jadeite rock at Suihodo, with matsubaraite and rengeite.
Okayama: Pink to colorless or whitish, translucent to transparent lustrous crystals to 5mm, often equant euhedral, SW UV fluorescent yellow, weather out of white jadeite rock bodies in serpentine at Ohsakabe. Collectors pan the crystals out of stream sand, so specimens usually show no matrix.
Shiga: Highly unusual light brown zircon is found in granite pegmatite at Suishohdani on Tanokamiyama. Finely ribbed, biconical aggregates of radial structure, to 3cm, resembling nested acorn cups, of U-Th-bearing zircon, are embedded in a halo of red feldspar and black quartz.
Tottori: The lavender jadeite boulders at Tsunodani include whitish rectangular grains of zircon, 1 to 2mm, fluorescent yellow-orange under SW UV.
ZIRCONOLITE (jirukonoraito)
Iwate: At Kamineichi, associated with dolomitic marble.
ZOISITE (kai-ren-seki; thulite = tohren-seki)
Ehime: Associated with hornblende, kyanite (qv), paragonite and margarite, in amphibolite at Tohnaru. Massive whitish zoisite is a major component of rock with amphibole and "ruby" (qv Corundum) in the Hodono valley. Also at the nearby Besshi mine.
Fukuoka: The light pink Mn-bearing variety, "thulite", occurs as vuggy crystalline masses composed almost entirely of prismatic-acicular "thulite" crystals (mostly micro, up to 1mm, rare crystals to 8mm) embedded in brownish white matrix, in Sangun metamorphic belt rocks (metamorphosed serpentines, dunite and amphibolite) in Sasaguri-machi and Kasuya-machi.
ZUNYITE (zuni-ishi; zuni-seki)
Iwate: A supposed new hydrous Al silicate mistakenly described in 1922 as "KOCHITE" from Kouchi-mura (whence the name), now part of Ishidoriya-cho, was shown in 1925 to be zunyite. Forms white octahedral crystals, 0.01 to 0.05mm; RI 1.590; D 2.932. Wt% Cl 2.91, F 5.18, with very minor Fe''', Ca, Mg. "Kochite" is also used (more legitimately) as a rock name for the brecciated and very altered Miocene rhyolite here, composed of a mixture of zunyite, diaspore, sericite, etc.
Nagano: Abundant colorless to white, simple tetrahedrons to 4mm (but normally only 1.5mm), are disseminated in hypogene acid alteration halo at the Shinyoh mine, where quartz diorite porphyry intruded Miocene pyroclastics. Associated with pyrophyllite, kaolinite, diaspore and quartz. Also reported in Saku, and at the Kanakura mine, the Kobayashi mine, and the Shiga mine. Embedded in brown fine-grained matrix at the Yochi (Yoji) mine (misnomer for the Shinyoh mine?).
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