Dictionary of Geotourism

2020 Edition
| Editors: Anze Chen, Young Ng, Erkuang Zhang, Mingzhong Tian

Sanidine

Reference work entry
DOI: https://doi.org/10.1007/978-981-13-2538-0_2146

The main composition of sanidine is K[AlSi3O8], and it always contains some Na[AlSi3O8]. Because it forms under high-temperature conditions, it is also called high-temperature sanidine. It crystallizes in the monoclinic crystal system, and crystal twinning is common. It is light white or colourless with white streaks. Its diaphaneity is translucent with a vitreous lustre. Its specific gravity is 2.56–2.62, and its Mohs hardness is 6. It usually forms in extrusive rocks such as trachyte and rhyolite and sometimes in contact-metamorphosed rocks.

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