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KAlSi3O8 An alkali feldspar mineral occurring in clear, glassy crystals embedded in unaltered acid volcanic rocks; a high-temperature, disordered form. Also known as glassy feldspar; ice spar; rhyacolite.



a rock-forming, monoclinic variety of feldspar; it is a solid solution of KAlSi3O8 and NaAlSi3O8, with the content of the potassium component ranging from 100 to 37 percent and a disordered distribution of Al and Si in the structure. At less than 37 percent KAlSi3O8, the structure becomes triclinic (high-temperature albite). In solid solution, sanidine contains up to 5–10 percent CaAl2Si2O8. Sanidine is one of the chief minerals of young extrusive and hypabyssal acid rocks (seeFELDSPAR).

References in periodicals archive ?
2010) suggested that fine ash cools rapidly, resulting in volcanic glass, whereas larger particles cool more slowly, resulting in sanidine and mica.
The feldspathoids nepheline and balliranoite, zeolite analcime and feldspar sanidine, which include Na in their chemical composition, may be the minerals that release Na, making it available in solution.
One variety of lamproite, rich in enstatite, sanidine and phlogopite, is referred to as Cancalite or Cancarixite due to its occurrence at the Volcano of Cancarix (Parga-Pondal, 1935; Fuster et al.
74 for sanidine, concluding that there is uniformity in the sample data.
Sheffield is planning preliminary metallurgical testwork to evaluate the process required to extract potassium from the sanidine feldspar to produce muriate of potash or sulphate of potash products.
50, in six limited-edition shades as part of the Jewels of the Earth collection - Crushed Citrine, Terraverte (pictured) Sanidine, Azurite, and Jade, www.
Albite, sanidine, Sb and ZnS were used as standards.
The sanidine composition has been studied in twelve drill-cores with an aim to identify the ash beds in the Telychian of Estonia.
The presence of plutonic detritus is confirmed by the occurrence of sparse K-feldspar grains with optic axial angles (2V) too high for volcanic sanidine.
Despite the inclusion of statements such as 'all contain sanidine in the groundmass as well as significant amounts of plagioclase .