mineral

Orthoclase Feldspar (Salmon variety)

Orthoclase, KAlSi3O8

Hardness: 6 (Mohs scale); Color: Salmon pink, peach, or orange-ish; Luster: Vitreous to pearly; Crystal structure: Monoclinic; Cleavage: Perfect at two directions forming 90-degree angles; Specific Gravity: 2.55-2.63

Hardness: 6 (Mohs scale)
Color: Salmon pink, peach, or orange-ish
Luster: Vitreous to pearly

Identified April 7, 2026More mineral →

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Physical properties

Formation & geological history

Formed primarily in plutonic igneous rocks like granite and syenite through slow cooling of magma. Can also be found in high-grade metamorphic rocks. Geological age varies greatly from Precambrian to Cenozoic depending on the host rock formation.

Uses & applications

Mainly used in the manufacture of glass and ceramics (porcelain and glaze). Occasionally used as a gemstone (Moonstone is a variety) or decorative stone in interior architecture.

Geological facts

Orthoclase is one of the ten defining minerals on the Mohs scale of mineral hardness. The name is derived from the Greek words for 'straight fracture', referring to its two cleavage planes at right angles to each other.

Field identification & locations

Identify in the field by its blocky shape, salmon-pink color, and flat, reflective cleavage surfaces that shimmer under bright light. It is common in granite-rich mountain ranges and pegmatites worldwide.

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