igneous
Rounded black-and-cream granite pebble
Granite, composed chiefly of quartz, feldspar, and dark mica or amphibole
AI-generated identification · may be incorrectCoarse-grained, speckled cream, gray, and black; likely Mohs 6–7, vitreous to dull luster, interlocking crystals, and no prominent cleavage as a whole. The rounded shape reflects water or sediment abrasion, possibly with surface weathering.
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Physical properties
Coarse-grained, speckled cream, gray, and black; likely Mohs 6–7, vitreous to dull luster, interlocking crystals, and no prominent cleavage as a whole. The rounded shape reflects water or sediment abrasion, possibly with surface weathering.
Formation & geological history
An intrusive igneous rock that crystallized slowly from silica-rich magma deep in Earth’s crust, commonly during Precambrian to Phanerozoic tectonic activity. It was later exposed by uplift and erosion.
Uses & applications
Used widely as dimension stone, countertops, monuments, paving, aggregate, and landscaping material; this small pebble has mainly educational or decorative value.
Geological facts
Visible light feldspar and darker mafic minerals are characteristic of granite. Exact identification from a photograph is approximate; similar granitic rocks include granodiorite and tonalite.
Field identification & locations
Identify it by its randomly interlocking, visible crystals and lack of layering or foliation; quartz should resist scratching by a steel knife, while feldspar commonly appears pink, white, or cream. Common in continental mountain belts and glacial or river gravels.
