igneous
Granite Cobble
Phaneritic Felsic Igneous Rock
Hardness: 6-7 on Mohs scale. Color: Salt and pepper (mottled grey, white, and black). Luster: Dull (weathered/smooth) to vitreous (on fresh breaks). Crystal Structure: Phaneritic (visible crystals of quartz, feldspar, and mica).
- Hardness
- 6-7 on Mohs scale
- Color
- Salt and pepper (mottled grey, white, and black)
- Luster
- Dull (weathered/smooth) to vitreous (on fresh breaks)
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Salt and pepper (mottled grey, white, and black). Luster: Dull (weathered/smooth) to vitreous (on fresh breaks). Crystal Structure: Phaneritic (visible crystals of quartz, feldspar, and mica).
Formation & geological history
Formed from the slow cooling and crystallization of magma deep beneath the Earth's surface. This specimen has been significantly rounded and smoothed by water transport (fluvial or beach erosion) over hundreds to thousands of years.
Uses & applications
Used in construction as aggregate, for decorative landscaping, and occasionally as worry stones or for crafts when found as river pebbles.
Geological facts
Granite is the primary component of the Earth's continental crust. Because of its quartz content, it is highly resistant to chemical weathering compared to many other rock types.
Field identification & locations
Identify in the field by its 'salt and pepper' appearance and the presence of quartz and feldspar crystals. Commonly found in riverbeds, glacial tills, and along coastlines near crystalline mountain ranges.
