igneous
Graphic Granite (Runic Granite)
Pegmatite (Graphic Granite variety)
Hardness: 6-6.5 (Mohs scale); Color: Pinkish-tan background with black or grey patterns; Luster: Vitreous to dull; Crystal structure: Monoclinic and Trigonal; Cleavage: Good in two directions (feldspar)
- Hardness
- 6-6
- Color
- Pinkish-tan background with black or grey patterns
- Luster
- Vitreous to dull
Identified More igneous →
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Physical properties
Hardness: 6-6.5 (Mohs scale); Color: Pinkish-tan background with black or grey patterns; Luster: Vitreous to dull; Crystal structure: Monoclinic and Trigonal; Cleavage: Good in two directions (feldspar)
Formation & geological history
Formed from the slow cooling of magma in pegmatites, where quartz and feldspar crystals intergrow simultaneously. This specific texture is often attributed to eutectic crystallization.
Uses & applications
Primarily used as a decorative stone for lapidary work, jewelry (cabochons), and collection specimens. Historically used in architectural veneer and as a unique countertop material.
Geological facts
The name 'graphic' comes from the Greek word 'graphos', meaning writing, because the dark quartz inclusions within the lighter feldspar matrix resemble ancient cuneiform or runic script.
Field identification & locations
Identified by the distinct 'writing' pattern on the surface. Commonly found in pegmatite districts such as Maine (USA), Norway, South Africa, and Russia. Field identification relies on the interlocking angular patterns.
