Formula: K(AlSi3O8) tectosilicate (framework silicate)
Sanidine is a high-temperature K-feldspar.
Specific gravity: 2.53 to 2.56
Colour: Colourless, transparent to opaque grey, grey brownish
Solubility: Insoluble in hydrochloric, sulphuric and nitric acid
Volcanic igneous environments
Sanidine occurs as phenocrysts (larger crystals embedded in a finer-grained matrix in an igneous rock) in
volcanic igneous rocks such as
rhyolite and trachyte. It is
rocks that cooled quickly from an initial high temperature of eruption.
Sanidine may occur in hornfels.
It is characteristic of the sanidinite facies.
Common impurities: Fe,Ca,Na,H2O
Back to Minerals