Sanidine is the high temperature form of potassium feldspar with a general formula K(AlSi3O8).[2] Sanidine is found most typically in felsic volcanic rocks such as obsidian, rhyolite and trachyte. Sanidine crystallizes in the monoclinic crystal system. Orthoclase is a monoclinic polymorph stable at lower temperatures. At yet lower temperatures, microcline, a triclinic polymorph of potassium feldspar, is stable.
Due to the high temperature and rapid quenching, sanidine can contain more sodium in its structure than the two polymorphs that equilibrated at lower temperatures. Sanidine and high albite constitute a solid solution series with intermediate compositions termed anorthoclase. Exsolution of an albite phase does occur; resulting cryptoperthite can best be observed in electron microprobe images.
Sanidine is the high temperature form of potassium feldspar with a general formula K(AlSi3O8). Sanidine is found most typically in felsic volcanic rocks...
fine-grained groundmass. The mineral assemblage is predominantly quartz, sanidine, and plagioclase. It is the extrusive equivalent of granite. Its high silica...
by barium. The first of these include: orthoclase (monoclinic) KAlSi3O8 sanidine (monoclinic) (K,Na)AlSi3O8 microcline (triclinic) KAlSi3O8 anorthoclase...
sanidine (anorthoclase) and is often cryptoperthitic, with alternating microscopic bands of sodium feldspar (albite) and potassium feldspar (sanidine)...
called perthite. The higher-temperature polymorph of KAlSi3O8 is sanidine. Sanidine is common in rapidly cooled volcanic rocks such as obsidian and felsic...
potassium- and titanium-rich richterite; low aluminium diopside; and iron-rich sanidine. A variety of rare trace minerals occur. The rocks are high in potassium...
albite – sanidine alkali feldspar solid solution series. Intermediate members of this series, high albite, anorthoclase and high sodium sanidine are stable...
chemically the same as orthoclase, but with a different crystalline structure Sanidine, the high-temperature form of potassium feldspar (K,Na)(Si,Al)4O8 Adularia...
minerals found in the pumice clasts are biotite, plagioclase, quartz, and sanidine. The main composition is SiO2 (73.4-77.9%), followed by Al2O3 (12.7%)....
(nepheline, sodalite, hauyne, leucite and analcite) and alkali feldspar (sanidine, anorthoclase or orthoclase), and rare sodic plagioclase. Biotite, sodium-rich...
characterized by dominant analcime phenocrysts in a matrix of analcime, sanidine and alkalic pyroxene with accessory titanite, melanite and nepheline. It...
and plagioclase phenocrysts in a groundmass with calcic plagioclase and sanidine and some dark-colored volcanic glass. Shoshonite gives its name to the...
eruptions, two common methods of radiometric dating are employed: 40Ar/39Ar on sanidine and U–Pb on zircon. The interpretation of the two techniques differs in...
plagioclase in dacite ranges from oligoclase to andesine and labradorite. Sanidine occurs, although in small proportions, in some dacites, and when abundant...
of orthoclase; it is more stable at lower temperatures than orthoclase. Sanidine is a polymorph of alkali feldspar stable at yet higher temperature. Microcline...
radiometrically dated to 18.78 +/- 0.02 Ma using argon-argon dating methods on sanidine crystals. The Peach Spring Tuff has a rhyolitic composition with thickness...
metamorphosed iron formations. It commonly occurs in association with orthoclase, sanidine, labradorite, olivine, leucite, amphiboles and other pyroxenes. Occasional...
pyroclastic rocks in which alkalis predominate over Ca, K-feldspar such as sanidine or albite Na-feldspar are found. Leucite is present in the K-rich, silica-poor...
named according to the percentage of quartz, alkali feldspar (orthoclase, sanidine, or microcline) and plagioclase feldspar on the A-Q-P half of the diagram...
chamber assembly at Yellowstone based on 40Ar/39Ar and U-Pb dating of sanidine and zircon crystals". Geochemistry, Geophysics, Geosystems. 16 (8): 2508–2528...
Forsterite Forsterite (big tabular and colorless) on sanidine (little colorless crystals) with hematite (reddish) General Category Nesosilicates Formula...
precision 40Ar/39Ar ages for Fish Canyon Tuff and Alder Creek Rhyolite sanidine: New dating standards required?". Geochimica et Cosmochimica Acta. 121:...
1016/j.palaeo.2008.09.013. Bogaard, Paul van den (1995). "40Ar/39Ar ages of sanidine phenocrysts from Laacher See Tephra (12,900 yr BP): Chronostratigraphic...
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