igneous
Granite pebble
Coarse-grained felsic intrusive igneous rock; mainly quartz, alkali feldspar, plagioclase, and minor biotite or amphibole
AI-generated identification · may be incorrectHardness about 6–7 Mohs; pink, gray, white, and black granular appearance with a glassy-to-dull luster. Crystals are interlocking and lack cleavage as a whole, though feldspar crystals may cleave.
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Physical properties
Hardness about 6–7 Mohs; pink, gray, white, and black granular appearance with a glassy-to-dull luster. Crystals are interlocking and lack cleavage as a whole, though feldspar crystals may cleave.
Formation & geological history
Formed by slow cooling of silica-rich magma deep in Earth’s crust, commonly during Precambrian to Phanerozoic mountain-building events; later weathered into a rounded stream or beach pebble.
Uses & applications
Used as crushed aggregate, road stone, building stone, countertops, monuments, and decorative landscaping material; this rounded specimen has little commercial value.
Geological facts
Its speckled texture reflects visible quartz and feldspar crystals, while pink coloration usually comes from potassium feldspar. The rounded shape indicates prolonged abrasion during transport.
Field identification & locations
Identify it by its coarse interlocking crystals, quartz-rich pale color, and pink feldspar; it is not likely basalt, which is darker and fine-grained. Common worldwide, especially in continental shields and mountain belts.
