igneous
Pegmatite or Graphic Granite
Intrusive Igneous Rock
Hardness on Mohs scale ranges from 6 to 7. Displays a mix of pinkish-red feldspar and dark black biotite or hornblende crystals. Luster is vitreous to dull. Crystalline structure is phaneritic with interlocking coarse-grained crystals.
Identified More igneous →
Explore Pegmatite or Graphic Granite in the encyclopedia →Identify your own rocks.
Get a report just like this from any photo, free.
Physical properties
Hardness on Mohs scale ranges from 6 to 7. Displays a mix of pinkish-red feldspar and dark black biotite or hornblende crystals. Luster is vitreous to dull. Crystalline structure is phaneritic with interlocking coarse-grained crystals.
Formation & geological history
Formed from the slow cooling of magma rich in water and other volatiles deep within the Earth's crust, typically associated with the late stages of magmatic crystallization.
Uses & applications
Used as a source of rare-earth elements, industrial minerals like mica and feldspar, gemstones, and as ornamental stone.
Geological facts
Pegmatites are known for containing exceptionally large crystals and rare minerals due to the high fluid content that allows rapid crystal growth.
Field identification & locations
Can be identified in the field by its extremely coarse-grained texture with distinct contrasting mineral patches such as pink potassium feldspar and dark micas. Found globally in continental shields and mountain-building belts.
