Sanidine Value, Price, and Jewelry Information

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Yellow-green Sanidine crystal from the small finds at Itrongay, Madagascar. Weighs 20 grams or 100 carats. By Rob Lavinsky, iRocks.com – CC-BY-SA-3.0 [CC-BY-SA-3.0], via Wikimedia Commons

Sanidine Information

Data	Value
Name	Sanidine
Is a Variety of	Orthoclase
Colors	Colorless, sometimes brown or yellow.
Fracture	Uneven to splintery, Parting common
Hardness	6-6.5
Cleavage	Perfect and easy in two directions
Wearability	Poor
Crystallography	Monoclinic.
Refractive Index	1.516-1.526
Birefringence	0.003-0 .007
Dispersion	None.
Luminescence	None.
Luminescence Present	No
Absorption Spectrum	Not diagnostic.
Pleochroism	None.
Optics	Biaxial (-). 2V = 18-54º.
Optic Sign	Biaxial -
Luster	Vitreous.
Specific Gravity	2.57-2.58
Transparency	Transparent to translucent.

Comments

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.

Name

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°.

Occurrence

A component of acid igneous rocks. Oregon; California.
Near Koblenz, Germany: brown transparent gems; S.G. 2.57-2.58; birefringence 0.007; indices: 1.516-1.520/ 1.520-1.525/1.522-1.526.
Ashton, Idaho: sanidine crystals in volcanic luff, up to 1 cm, colorless, well formed. Indices: 1.516-1.519/ 1.520-1.522/1.521-1.523; 2V=8-19°; birefringence 0.003-0.005.

Stone Sizes

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.