igneous
Graphic Granite (or Pegmatite with Tourmaline/Biotite)
Alkali-feldspar granite pegmatite
AI-generated identification · may be incorrectHardness of 6-7 on the Mohs scale, vitreous to pearly luster, distinct pinkish-orange feldspar, translucent quartz, and dark black tourmaline or biotite mica inclusions. Crystalline structure is phaneritic and pegmatitic.
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Physical properties
Hardness of 6-7 on the Mohs scale, vitreous to pearly luster, distinct pinkish-orange feldspar, translucent quartz, and dark black tourmaline or biotite mica inclusions. Crystalline structure is phaneritic and pegmatitic.
Formation & geological history
Formed from the slow cooling of silica-rich magma deep within the Earth's crust, typically during the final stages of crystallization of a magmatic intrusion.
Uses & applications
Used as ornamental stone, lapidary material for cabochons and decorative objects, and sought after by mineral collectors.
Geological facts
Graphic granite gets its name because the dark mineral intergrowths often resemble ancient cuneiform or runic writing when cut in certain directions.
Field identification & locations
Easily identified by the stark contrast between the pink/red potassium feldspar, clear quartz, and dark prismatic or flaky crystals. Commonly found in pegmatite dikes worldwide, especially in regions with ancient cratons like parts of Canada, Scandinavia, and the USA.
