|Is a Variety of||Orthoclase|
|Colors||Colorless, sometimes brown or yellow.|
|Fracture||Uneven to splintery, Parting common|
|Cleavage||Perfect and easy in two directions|
|Transparency||Transparent to translucent.|
|Absorption Spectrum||Not diagnostic.|
Biaxial (-). 2V = 18-54º.
|Optic Sign||Biaxial -|
Sanidine is a mineral of volcanic rocks, with little gem significance. It is uncommon and rarely seen as a gem. While occasionally brown or yellow, most examples are colorless. While the properties are closer to microcline, it is usually classed as a plagioclase.
Sanidine is also from the Greek, sanis, meaning board, in reference to the tabular crystals. Anorthoclase is from Greek words for not upright because the cleavage is not 90°.
Sanidine is not a common mineral and is hardly ever seen as a gemstone. Crystals tend to be colorless and nondescript and are rare in cuttable sizes.