| JaLCDOI | 10.18926/ESR/13894 |
|---|---|
| Title Alternative | Native gold from Mikawa mine, Niigata Prefecture, Japan |
| FullText URL | ESR_7_19.pdf |
| Author | Yamakawa, Junji| Tanabe, Mitsuo| Shimada, Kazumasa| Henmi, Chiyoko| |
| Abstract | Native gold was found at Mikawa mine, Niigata Prefecture, Japan. The mineral was associated with quartz in a druse within quartz-vein in propyrite. The crystals were formed in filiform, reticulated and dendritic shapes with about 1 mm length with 0.1 mm width and 0.05 mm thickness. Very malleable and ductile, opaque and yellow with metallic luster. Qualitative and semi-quantiative analyses were performed by the wavelength dispersive EPMA. Quantitatively, the crystals contained Au, Ag and Hg. Semi-quantitative analyses were executed with ZAF correction algorithm. The results showed that these specimens had a average chemical composition Au0.77 Ag0.11Hg0.12. This specimen was archived at our site with a collection number ESO-M01001. |
| Keywords | Native Gold Mikawa Mine electrum ESO-M01001 |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2000-09-20 |
| Volume | volume7 |
| Issue | issue1 |
| Start Page | 19 |
| End Page | 20 |
| ISSN | 1340-7414 |
| language | Japanese |
| Copyright Holders | 岡山大学地球科学研究報告編集委員会 |
| File Version | publisher |
| NAID | 120002310280 |
| JaLCDOI | 10.18926/ESR/13899 |
|---|---|
| FullText URL | ESR_7_27.pdf |
| Author | Henmi, Chiyoko| Kusachi, Isao| Kagetama Tatsuya| |
| Abstract | The clinopyroxenes of the hybrid rocks from the Hirata outcrop, Kushiro, Hiroshima Prefecture, Japan are grouped into(1)diopside, (2)aegirine, and (3)zoned pyroxene. The diopside occurs as isolated crystals enclosed in feldspars. The aegirine occurs along with late hydrous minerals in pore spaces. The zoned pyroxenes occur as discrete cryatals with wide rims growing interstitially between feldspar laths and show a continuous composition-al trend from diopside through hedenbergite and aegirine-augite to aegirine or titanian aegirine. The pyroxenes enclosed in feldspars and the cores of the zoned crystals have nearly same chemical composition. The late stage pyroxenes are characterized by extreme enrichment of sodium and sometimes titanium. The titanian aegirines studied hera are characterized by the predominance of the Na(Fe2+, Mg)0.5Ti0.5Si2O6 component over other Ti-bearing pyroxene components. The compositional trend of clinopyroxenes from the Hirata hybrid rocks follows a typical trend of peralkalne rocks. The peralkaline neture of the Hirata samples is a result of compositional change of magma accompanied by the metasomatic skarn formation. |
| Keywords | aegirine aegirine-augite diopside pyroxene hybrid rock skarn |
| Publication Title | Okayama University Earth Science Report |
| Published Date | 2000-09-20 |
| Volume | volume7 |
| Issue | issue1 |
| Start Page | 27 |
| End Page | 34 |
| ISSN | 1340-7414 |
| language | English |
| Copyright Holders | 岡山大学地球科学研究報告編集委員会 |
| File Version | publisher |
| NAID | 120002310313 |
