igneous
Weathered feldspar-rich pegmatite (likely orthoclase or plagioclase)
Granitic pegmatite; predominantly K-feldspar/plagioclase (KAlSi₃O₈–NaAlSi₃O₈), with quartz and dark mafic minerals
AI-generated identification · may be incorrectHardness about 6–6.5; cream to salmon coloration, dull-to-glassy luster, coarse interlocking crystals, and prominent feldspar cleavage. Dark spots likely biotite, amphibole, or iron/manganese staining; the surface is strongly weathered.
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Physical properties
Hardness about 6–6.5; cream to salmon coloration, dull-to-glassy luster, coarse interlocking crystals, and prominent feldspar cleavage. Dark spots likely biotite, amphibole, or iron/manganese staining; the surface is strongly weathered.
Formation & geological history
Formed when silica-rich magma crystallized slowly in a pegmatite body, producing large feldspar crystals; the specimen’s age depends on its locality, commonly Precambrian to Mesozoic. Weathering altered and stained the exposed surface.
Uses & applications
Used as a source of feldspar for glass and ceramics, and occasionally as decorative stone or a mineral-collecting specimen; this small weathered piece has limited commercial value.
Geological facts
Pegmatites can contain exceptionally large crystals and rare minerals such as tourmaline, beryl, lithium minerals, or tantalum minerals. Feldspar cleavage surfaces commonly appear smooth and blocky.
Field identification & locations
Identify it by its coarse texture, blocky cleavage, pale color, and hardness below quartz; a steel file may scratch it, while quartz generally will not. Common in granitic terrains worldwide, especially pegmatite districts.
