mineral

Cleaved feldspar crystal (likely plagioclase)

Plagioclase feldspar, approximately NaAlSi₃O₈–CaAl₂Si₂O₈ solid solution

AI-generated identification · may be incorrect

Creamy white to pale tan, opaque, with a vitreous-to-pearly luster and prominent cleavage in two directions near 90°. Hardness 6–6.5 Mohs; triclinic crystal structure. The specimen’s appearance alone cannot confirm feldspar species.

Identified September 29, 2026More mineral →

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Physical properties

Formation & geological history

Feldspar crystallizes from cooling magma and occurs in igneous rocks; it also forms in metamorphic rocks. Its geological age depends on its source rock and cannot be determined from the image.

Uses & applications

Feldspar is widely used in ceramics and glass manufacture; attractive crystals are collected, and some feldspar varieties are used as gemstones.

Geological facts

Feldspar is the most abundant mineral group in Earth’s crust. Plagioclase ranges from sodium-rich albite to calcium-rich anorthite.

Field identification & locations

Look for blocky shape and two intersecting cleavage planes; plagioclase may show fine parallel striations on cleavage faces. Common in granite, basalt, and many metamorphic rocks worldwide.