igneous
Granite pebble
Granite, typically quartz–feldspar–mica aggregate
AI-generated identification · may be incorrectCoarse-grained, speckled gray-and-black appearance with pale feldspar/quartz and dark biotite or amphibole. Mohs hardness about 6–7; generally vitreous to dull luster, massive texture, no cleavage as a whole, and specific gravity around 2.6–2.7.
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Physical properties
Coarse-grained, speckled gray-and-black appearance with pale feldspar/quartz and dark biotite or amphibole. Mohs hardness about 6–7; generally vitreous to dull luster, massive texture, no cleavage as a whole, and specific gravity around 2.6–2.7.
Formation & geological history
An intrusive igneous rock crystallized slowly from silica-rich magma deep underground, commonly during Precambrian to younger continental crust formation. Its rounded shape indicates transport and abrasion in stream, beach, or weathered regolith.
Uses & applications
Used as crushed aggregate, road stone, building stone, paving, countertops, and decorative material. This small naturally rounded specimen has minimal commercial value.
Geological facts
The visible black-and-white “salt-and-pepper” texture is characteristic of granitoid rocks. It may technically be granodiorite or tonalite if quartz and plagioclase dominate, distinctions that require a larger fresh surface or laboratory analysis.
Field identification & locations
Consistent with granitic rocks and transported cobbles possible near 6.9°N, 126.0°E in eastern Mindanao, though the image alone cannot establish provenance. A glassy quartz grain, feldspar cleavage, and interlocking crystals support granite; a streak, acid test, and thin section would improve identification.
