Oligoclase is a rock-forming mineral belonging to the plagioclase feldspars. In chemical composition and in its crystallographic and physical characters...
5 KB (496 words) - 17:48, 28 October 2024
Sunstone is a microcline or oligoclase feldspar, which when viewed from certain directions exhibits a spangled appearance. It has been found in Southern...
8 KB (692 words) - 08:51, 1 November 2023
Gotthard.[better source needed] A solid solution of the plagioclase feldspar oligoclase +/− the potassium feldspar orthoclase also produces moonstone specimens...
6 KB (466 words) - 02:21, 4 November 2024
silica and related volcanics such as andesite. Oligoclase is common in granite and monzonite. The name oligoclase is derived from the Greek olígos ('small,...
25 KB (2,886 words) - 00:30, 29 October 2024
Osumilite Otavite Ottrelite Otwayite Varieties that are not valid species: Oligoclase (a mixture of albite and anorthite) Onyx (a monochromatic banded variety...
42 KB (2,782 words) - 15:04, 6 November 2024
plagioclase is typically intermediate to sodic in composition, andesine to oligoclase. Quartz is present in significant amounts. Biotite and/or hornblende constitute...
4 KB (435 words) - 18:59, 19 January 2024
follows (with percent anorthite in parentheses): albite (0 to 10) NaAlSi3O8 oligoclase (10 to 30) (Na,Ca)(Al,Si)AlSi2O8 andesine (30 to 50) NaAlSi 3O 8 – CaAl...
25 KB (2,434 words) - 12:50, 9 November 2024
than 1 millimeter. The plagioclase is sodium-rich, usually albite or oligoclase. These quartz-plagioclase intergrowths are associated with and commonly...
12 KB (1,508 words) - 14:21, 29 September 2023
produced by hydrothermal alteration of basalt, and composed of albite or oligoclase, together with chlorite, epidote, calcite, and actinolite. Spilite is...
2 KB (179 words) - 21:11, 26 October 2024
K)AlSi3O8 Sanidine – KAlSi3O8 Plagioclase feldspars Albite – NaAlSi3O8 Oligoclase – (Na,Ca)(Si,Al)4O8 (Na:Ca 4:1) Andesine – (Na,Ca)(Si,Al)4O8 (Na:Ca...
20 KB (1,897 words) - 18:21, 16 July 2024