igneous
Granite / Pegmatite Pebble
Felsic intrusive igneous rock
Hardness: 6-7 on the Mohs scale. Color: Mixture of pink/red (potassium feldspar), white/grey (quartz or plagioclase), and greenish or dark specks. Luster: Vitreous to dull. Crystal structure: Phaneritic (coarse-grained, interlocking crystals). Cleavage: Varies by mineral component. Specific gravity: ~2.65-2.75.
- Hardness
- 6-7 on the Mohs scale
- Luster
- Vitreous to dull
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Physical properties
Hardness: 6-7 on the Mohs scale. Color: Mixture of pink/red (potassium feldspar), white/grey (quartz or plagioclase), and greenish or dark specks. Luster: Vitreous to dull. Crystal structure: Phaneritic (coarse-grained, interlocking crystals). Cleavage: Varies by mineral component. Specific gravity: ~2.65-2.75.
Formation & geological history
Formed from the slow cooling and solidification of magma rich in silica and alkali metals deep beneath the Earth's crust, often dating from the Precambrian to Cenozoic eras, subsequently weathered and tumbled in a river or marine environment.
Uses & applications
Commonly used in construction, monuments, countertops, and landscaping. Natural tumbled pebbles are used in decorative landscaping and as decorative display pieces.
Geological facts
Granite is the most common rock of the Earth's continental crust. Pegmatites often host rare minerals and large, well-formed crystals due to the slow crystallization in water-rich magma environments.
Field identification & locations
Easily identified in the field by its distinct speckled appearance, featuring interlocking crystals of pink feldspar and translucent quartz. Common worldwide in glacial tills, riverbeds, and beach gravels.
