igneous
Tumbled feldspar–quartz rock, possibly granite or pegmatite
Feldspar (orthoclase/plagioclase) + quartz, with dark biotite or hornblende
AI-generated identification · may be incorrectHardness about 6–7 Mohs; cream to honey-yellow, with translucent granular areas and black mineral inclusions; vitreous to pearly luster and no obvious cleavage on the polished surface. The rounded shape indicates tumbling or natural abrasion.
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Physical properties
Hardness about 6–7 Mohs; cream to honey-yellow, with translucent granular areas and black mineral inclusions; vitreous to pearly luster and no obvious cleavage on the polished surface. The rounded shape indicates tumbling or natural abrasion.
Formation & geological history
Likely an evolved igneous rock formed by slow cooling of silica-rich magma, allowing coarse crystals to grow; commonly Paleozoic to Precambrian in age depending on source. Yellow coloration may reflect iron staining or weathering.
Uses & applications
Used mainly as a decorative tumbled stone, teaching specimen, or lapidary material; similar granite and pegmatite are widely used for countertops, monuments, and aggregate.
Geological facts
The pale grains are probably feldspar and quartz, while the black patches are mafic minerals such as biotite or hornblende. Exact identification requires a fresh surface, streak, hardness testing, and possibly thin-section analysis.
Field identification & locations
Look for interlocking pale crystals, glassy quartz, and scattered black flakes or grains; granite is typically visibly granular, while pegmatite has unusually large crystals. Common worldwide, especially in granitic terrains.
