Chemical Formula KAlSi3O8
Color Green, Yellow
Hardness 6 – 6.5
Crystal System Monoclinic
Refractive Index 1.52 – 1.53
SG 2.56 – 2.59
Transparency Transparent
Double Refraction -.008
Luster Vitreous
Cleavage 2,1 – basal ; 2,1 – prismatic ; 3,1 – pinacoidal
Mineral Class Sanidine

The color of Orthoclase gemstones is natural and is not enhanced by heat treatment. Occasionally the colorless, transparent forms from Switzerland are also cut as gemstones, but in general Orthoclase gemstones are yellow. Some Orthoclase gems display a cat’s eye effect when cut into cabochon. Orthoclase may be fluorescent with a weak orange or bluish color.


Orthoclase is a rare gemstone and is faceted into gemstone cuts for jewelry such as pendants, earrings, and pins.


Noble OrthocloseOrthoclase gemstones are not treated or enhanced.Mostly from Madagascar, but also from Myanmar (Burma), Tanzania, and Brazil. The Madagascar locality provides the stones of the deepest color.Citrine, Heliodor, and Topaz are all softer.
Pearls have been highly valued as gemstones since antiquity, and their allure and beauty has always been magnified by the difficulty of obtaining them in early times. Unlike most other gemstones which are minerals, Pearls are organic and are formed by living organisms. They are generally formed within the soft tissue layer of mollusks such as oysters and mussels. Pearls are composed of calcium carbonate (in the form of Aragonite) and organic conchiolin that build up as concentric layers as they are secreted by their host.
Orthoclase SOURCES

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