igneous
Granite pebble
Granite, chiefly quartz, alkali feldspar, plagioclase, and mica
AI-generated identification · may be incorrectCoarse-grained, speckled light gray rock with a granular texture and mostly vitreous-to-dull luster. Hardness is about 6–7 Mohs; crystals are interlocking, with no prominent cleavage at the specimen scale.
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Physical properties
Coarse-grained, speckled light gray rock with a granular texture and mostly vitreous-to-dull luster. Hardness is about 6–7 Mohs; crystals are interlocking, with no prominent cleavage at the specimen scale.
Formation & geological history
An intrusive igneous rock formed by slow cooling of silica-rich magma deep in Earth’s crust, commonly during Precambrian to Phanerozoic mountain-building events. Its rounded shape indicates later erosion and transport, likely as a pebble.
Uses & applications
Used extensively as dimension stone, countertops, monuments, paving, aggregate, and landscaping material; small pieces have modest collecting value.
Geological facts
The visible glitter likely comes from quartz and mica grains. Granite commonly contains radioactive trace minerals such as zircon and may show pink feldspar or black biotite.
Field identification & locations
Identify it by its visible interlocking grains, hardness, and lack of layering or fossils; quartz typically scratches glass, while feldspar and mica provide contrasting white, gray, and dark grains. Common worldwide, especially in continental shields and mountain belts.
