igneous
Granite (weathered pebble)
Granite; primarily quartz, potassium feldspar, plagioclase, and mica
AI-generated identification · may be incorrectCoarse-grained, speckled tan-gray rock with vitreous quartz, pinkish feldspar, and dark mica/hornblende; Mohs hardness about 6–7, nonfoliated, with no prominent cleavage as a whole. Typically dense, massive, and crystalline, with specific gravity around 2.6–2.7.
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Physical properties
Coarse-grained, speckled tan-gray rock with vitreous quartz, pinkish feldspar, and dark mica/hornblende; Mohs hardness about 6–7, nonfoliated, with no prominent cleavage as a whole. Typically dense, massive, and crystalline, with specific gravity around 2.6–2.7.
Formation & geological history
An intrusive felsic igneous rock formed by slow cooling and crystallization of silica-rich magma deep within continental crust, commonly during Precambrian to younger geological periods. The rounded shape reflects transport and weathering, likely in a stream or glacial deposit.
Uses & applications
Widely used as dimension stone, countertops, monuments, paving, aggregate, and building stone; ordinary pebbles have little commercial value.
Geological facts
The visible interlocking crystals are characteristic of slow underground cooling. Quartz grains are usually glassy and gray, while feldspar commonly produces the pink or cream coloration.
Field identification & locations
Identify it by its coarse interlocking crystals, speckled appearance, hardness, and lack of layering or foliation; it will not fizz in dilute hydrochloric acid. Common worldwide, especially in continental mountain belts and exposed shield regions.
