igneous
Graphic Granite
Pegmatitic Granite
Hardness of 6-7 on Mohs scale; pink to white feldspar with dark quartz or biotite intergrowths resembling ancient cuneiform or runes; vitreous to pearly luster; granular to crystalline structure; specific gravity around 2.55-2.75.
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Physical properties
Hardness of 6-7 on Mohs scale; pink to white feldspar with dark quartz or biotite intergrowths resembling ancient cuneiform or runes; vitreous to pearly luster; granular to crystalline structure; specific gravity around 2.55-2.75.
Formation & geological history
Formed from the slow cooling of silica-rich magma in pegmatite dikes deep within the Earth's crust, allowing large crystals to intergrow simultaneously.
Uses & applications
Used primarily as decorative stone, lapidary material for cabochons and carvings, and educational specimens for studying eutectic crystallization.
Geological facts
The name 'graphic' comes from the striking visual resemblance of the mineral intergrowths to ancient written characters or runes.
Field identification & locations
Easily identified in the field by its distinct runic patterns of dark quartz embedded in pink or white alkali feldspar. Found worldwide in pegmatite-rich regions such as the Black Hills of South Dakota and various shield areas.
