igneous
Granite
Granite, chiefly quartz, feldspar, and mica (commonly biotite)
AI-generated identification · may be incorrectCoarse-grained, speckled white, gray, and black; vitreous to pearly luster. Hardness is approximately 6–7 Mohs, with interlocking crystals and no prominent cleavage as a whole; density is about 2.6–2.7 g/cm³.
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Physical properties
Coarse-grained, speckled white, gray, and black; vitreous to pearly luster. Hardness is approximately 6–7 Mohs, with interlocking crystals and no prominent cleavage as a whole; density is about 2.6–2.7 g/cm³.
Formation & geological history
An intrusive igneous rock formed when silica-rich magma cooled slowly deep underground, allowing visible crystals to grow. Individual pieces may range from Precambrian to younger Phanerozoic ages.
Uses & applications
Widely used for countertops, monuments, building stone, aggregate, and paving; attractive polished varieties are also collected. This small weathered specimen has minimal commercial value.
Geological facts
The white portions are usually quartz and feldspar, while black grains are commonly biotite or amphibole. Granite is the coarse-grained equivalent of volcanic rhyolite.
Field identification & locations
Identify it by visible interlocking crystals and abundant light feldspar/quartz with scattered dark mica or amphibole; it does not fizz in dilute acid. Common worldwide, especially in continental mountain belts and exposed batholiths.
