igneous
Granite pebble
Granite; chiefly quartz, alkali feldspar, plagioclase, and mica
AI-generated identification · may be incorrectCoarse-grained, speckled pink-gray rock with a granular texture; quartz has Mohs hardness 7, feldspar 6–6.5, and mica 2–3. Typically vitreous to pearly luster, interlocking crystals, no preferred cleavage as a whole, and specific gravity about 2.63–2.75.
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Physical properties
Coarse-grained, speckled pink-gray rock with a granular texture; quartz has Mohs hardness 7, feldspar 6–6.5, and mica 2–3. Typically vitreous to pearly luster, interlocking crystals, no preferred cleavage as a whole, and specific gravity about 2.63–2.75.
Formation & geological history
Granite forms when silica-rich magma slowly crystallizes deep in continental crust, commonly during Precambrian to younger mountain-building events. This rounded specimen was likely freed by weathering and transported by water or ice.
Uses & applications
Used extensively as dimension stone, countertops, monuments, paving, aggregate, and architectural cladding; small pieces are common educational and collecting specimens. Its value is usually modest unless unusually colorful or locally significant.
Geological facts
The visible pink grains are commonly potassium feldspar, gray translucent grains are quartz, and dark flakes are biotite or hornblende. Granite is the intrusive equivalent of volcanic rhyolite.
Field identification & locations
Identify it by its visible interlocking light and dark crystals, hardness, and lack of layering or foliation; it will not fizz with dilute hydrochloric acid. Common worldwide, especially in continental shields and mountain belts.
