Orthoclase identification and geology

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• Microcline
• Albite
• Calcite

Sources, scope & corrections

These authoritative resources support category-level nomenclature, terminology, identification methods, and safety. When a specimen-specific safety warning appears, the public-health source listed here directly supports that precaution. They are not line-by-line citations for every other property on this entry, and natural specimens vary.

Editorial owner

GeoMiner

Last updated

2026-03-30T14:36:43.581979+00:00

Review status

Published; not independently peer-reviewed

• IMA–CNMNC List of Mineral Names — International Mineralogical Association. Official mineral-name, nomenclature, and classification records.
• Mineral ID Key — Mineralogical Society of America. Physical-property identification methods, repeat-testing guidance, and limitations.

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Common questions

What is Orthoclase?

Common potassium feldspar and important rock-forming mineral. Defines hardness 6 on the Mohs scale.

How can you identify Orthoclase?

Compare several properties rather than relying on colour alone. This entry records colour: White, pink, yellow, gray; lustre: Vitreous to pearly; streak: White; Mohs hardness: 6; cleavage: Perfect in two directions at 90°; crystal system: Monoclinic; transparency: Translucent to opaque. Confirm an important identification with additional field tests or qualified laboratory work.

How does Orthoclase form?

Crystallizes from felsic magmas; common in granites, syenites, and rhyolites.

Where is Orthoclase commonly found?

Worldwide; major component of granite and many metamorphic rocks.

What is Orthoclase commonly confused with?

Orthoclase may be confused with Microcline, Albite, Calcite. Compare multiple diagnostic properties because colour and surface appearance can overlap.