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 英語
Copyright Holders 岡山大学地球科学研究報告編集委員会
File Version publisher
NAID 120002310313
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 日本語
Copyright Holders 岡山大学地球科学研究報告編集委員会
File Version publisher
NAID 120002310280