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Mineral formula: K(AlSi3O8)

Mineral group: member of the  feldspar group

Crystal system: monoclinic

Crystal habit: blocky, prismatic, massive or granular.

Cleavage: Perfect on {001}, good on {010} 

Fracture: irregular / uneven, conchoidal

Color: colorless to white, greenish white, pale pink, yellowish

Luster: vitreous, sub-vitreous, resinous

Diaphaneity: transparent, translucent

Moh’s scale hardness: 6

Streak: white

Specific gravity: 2.55 – 2.63

Named after: the Greek orthos ("right") in allusion to the mineral's right angle of good cleavage; Rene Just Haüy named it “orthose” in 1801. The sense of Haüy's name was that the mineral was a feldspar, but he did not specify a type-locality, nor did Haüy give a chemical analysis. The name was changed in 1823 to orthoklas by Johann Friedrich August Breithaupt.

Geological occurrence: Common feldspar of high-temperature granites, syenites, high-grade metamorphic rocks, and felsic extrusive rocks.

Energetic properties: As for all feldspars, orthoclase supports detaching from the old, with self-love and self-awareness. According to Melody,* orthoclase is a “stone of cooperative effort” assisting with regulating mood and keeping spirits high. It promotes liveliness and pleasantness