igneous
Granite Pebble
Granite (Phaneritic Quartz-Feldspar Plutonic Rock)
Hardness: 6-7 Mohs; Color: Speckled tan, orange, and gray; Luster: Dull to vitreous; Structure: Phaneritic (medium-grained crystalline); Primary minerals: Quartz, Orthoclase Feldspar, and minor biotite or hornblende.
- Hardness
- 6-7 Mohs
- Color
- Speckled tan, orange, and gray
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 Mohs; Color: Speckled tan, orange, and gray; Luster: Dull to vitreous; Structure: Phaneritic (medium-grained crystalline); Primary minerals: Quartz, Orthoclase Feldspar, and minor biotite or hornblende.
Formation & geological history
Formed by the slow cooling of silica-rich magma deep underground. These rocks are usually billions to hundreds of millions of years old and are exposed through erosion and tectonic uplift. This specific specimen has been rounded by water or glacial action.
Uses & applications
Large-scale use in construction (curbstones, flooring, countertops). Small pebbles are used in landscaping, gravel, and as filler for drainage systems.
Geological facts
Granite makes up the majority of the Earth's continental crust. Because it is resistant to acid rain and very durable, it is the primary material used for headstones and monuments worldwide.
Field identification & locations
Identify in the field by its 'salt and pepper' or speckled appearance with visible interlocking crystals that are roughly the same size. Commonly found in riverbeds, glacial tills, and mountain outcrops.
