igneous
Coarse-grained granite
Granite; predominantly quartz (SiO₂), feldspar, and mica/amphibole
AI-generated identification · may be incorrectLight gray, speckled, phaneritic texture with visible interlocking crystals and uneven fracture; quartz is Mohs 7, feldspar about 6, and mica 2–3. Typically has a glassy quartz luster and pale feldspar with dark mica or amphibole.
Identified More igneous →
Explore Coarse-grained granite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Light gray, speckled, phaneritic texture with visible interlocking crystals and uneven fracture; quartz is Mohs 7, feldspar about 6, and mica 2–3. Typically has a glassy quartz luster and pale feldspar with dark mica or amphibole.
Formation & geological history
Forms when silica-rich magma slowly cools and crystallizes deep within continental crust, commonly during Precambrian to Mesozoic intrusive events. The specimen appears weathered or freshly broken from a larger plutonic body.
Uses & applications
Widely used as dimension stone, countertops, monuments, aggregate, and building cladding; attractive pieces may be collected but this fragment has little commercial value.
Geological facts
Its coarse crystals indicate slow underground cooling, unlike fine-grained volcanic rhyolite. The dark minerals are likely biotite mica and/or hornblende, while the translucent grains are quartz.
Field identification & locations
Identify it by visible interlocking quartz, feldspar, and dark mica crystals, with no layering or foliation; a streak test is generally ineffective. Common worldwide, especially in continental mountain belts and exposed plutons.
