Chlorine-rich potassium hastingsite from West Ongul Island, Lfitzow-Holm Bay
Chlorine-rich potassium hastingsite occurs in a calcareous pegmatite, a replacement zone and an amphibolite l ns within hornblende gneiss on West Ongul Island, Lfitzow-Holm Bay, East Antarctica. The amphibolite l ns and hornblende gneiss were metamorphosed to the kyanite-sillimanite grade of the gra...
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| Format: | Text |
| Language: | English |
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| Online Access: | http://citeseerx.ist.psu.edu/viewdoc/summary?doi=10.1.1.616.4977 http://www.minersoc.org/pages/Archive-MM/Volume_51/51-363-709.pdf |
| Summary: | Chlorine-rich potassium hastingsite occurs in a calcareous pegmatite, a replacement zone and an amphibolite l ns within hornblende gneiss on West Ongul Island, Lfitzow-Holm Bay, East Antarctica. The amphibolite l ns and hornblende gneiss were metamorphosed to the kyanite-sillimanite grade of the granulite facies during Proterozoic metamorphism. Chemical analysis (3.27 wt. % C1), unit cell parameters and optical properties of the Cl-rich potassium hastingsite are given. Cl-rich (> 3 wt. %) calcic amphiboles reported from various rock types are mostly more than 0.9 in (Na+ K) content, more than 0.4 in K/(Na + K) ratio, more than 0.75 in Fe 2 +/(Fe 2 § + Mg + Mn) ratio and more than 1.9 in A1 iv content (total iron as FeO and O = 23). The unit cell volume of Cl-rich hastingsite is distinctly larger than that of Cl-poor hastingsite. KEYWOROS: Cl-rich calcic amphiboles, hastingsite, West Ongul Island, Antarctica. |
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