igneous
Granite pebble
Coarse-grained felsic plutonic rock; mainly quartz, potassium feldspar, plagioclase, and biotite/hornblende
AI-generated identification · may be incorrectHardness about 6–7 Mohs; speckled tan, cream, gray, and black appearance with a granular texture and vitreous-to-dull luster. Interlocking crystals show no foliation and generally lack cleavage as a whole rock.
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Physical properties
Hardness about 6–7 Mohs; speckled tan, cream, gray, and black appearance with a granular texture and vitreous-to-dull luster. Interlocking crystals show no foliation and generally lack cleavage as a whole rock.
Formation & geological history
Granite crystallizes slowly from silica-rich magma deep in continental crust, commonly during Precambrian to Phanerozoic mountain-building events. This rounded specimen was likely transported and smoothed by a river, beach, or glacial system.
Uses & applications
Used as crushed stone, building stone, countertops, monuments, and landscape material; this small pebble has mainly educational or decorative value.
Geological facts
Its visible grains indicate slow underground cooling rather than volcanic eruption. The dark minerals are likely biotite or hornblende, while the pale pink grains are potassium feldspar.
Field identification & locations
Identify it by coarse interlocking quartz-feldspar grains and black mica or amphibole, unlike fine-grained basalt. Common worldwide, especially in continental shields, mountain belts, river gravels, and glacial deposits.
