igneous

Pegmatitic Granite

Granite with Orthoclase Feldspar and Quartz (SiO2, KAlSi3O8)

Hardness: 6-7 (Mohs scale); Color: Pink (orthoclase), translucent white/gray (quartz); Luster: Vitreous to pearly; Crystal structure: Macro-crystalline/Phaneritic; Specific gravity: approx. 2.65-2.75

Hardness: 6-7 (Mohs scale)
Color: Pink (orthoclase), translucent white/gray (quartz)
Luster: Vitreous to pearly

Identified April 5, 2026More igneous →

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Physical properties

Hardness: 6-7 (Mohs scale); Color: Pink (orthoclase), translucent white/gray (quartz); Luster: Vitreous to pearly; Crystal structure: Macro-crystalline/Phaneritic; Specific gravity: approx. 2.65-2.75

Formation & geological history

Formed through the slow cooling of magma deep underground, specifically in the final stages of crystallization where large crystals grow from water-rich melts. Geological age ranges from Precambrian to Cenozoic depending on the specific batholith.

Uses & applications

Used in high-end construction, countertops, dimensional stone, and as a source for industrial minerals like feldspar for ceramics or quartz for silicon.

Geological facts

This specimen shows the 'graphic' texture common in pegmatites. The pink color comes from potassium feldspar (orthoclase), and the glassy areas are quartz. Granitic pegmatites are often the source of rare gemstones like beryl and tourmaline.

Field identification & locations

Identify by looking for very large interlocking crystals of pink feldspar and glassy quartz. Found in mountainous or shield areas with exposed plutonic rocks. Commonly found in waste piles of old mica or feldspar mines.

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