igneous
Granite Pebble
Granite; primarily composed of Quartz (SiO2), Feldspar (KAlSi3O8), and Mica
Hardness: 6-7 on Mohs scale. Color: Speckled white, grey, and black. Luster: Dull to vitreous. Structure: Phaneritic (coarsegrained, visible crystals) though water-worn in this specimen. Specific gravity: 2.63 - 2.75.
- Hardness
- 6-7 on Mohs scale
- Color
- Speckled white, grey, and black
- Luster
- Dull to vitreous
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Physical properties
Hardness: 6-7 on Mohs scale. Color: Speckled white, grey, and black. Luster: Dull to vitreous. Structure: Phaneritic (coarsegrained, visible crystals) though water-worn in this specimen. Specific gravity: 2.63 - 2.75.
Formation & geological history
Formed from the slow crystallization of magma below Earth's surface. This specific specimen has been shaped and smoothed by fluvial or coastal abrasion over hundreds to thousands of years.
Uses & applications
Used in construction as crushed stone or gravel, high-end countertops when in slab form, and as decorative landscaping stones.
Geological facts
Granite makes up a large portion of the Earth's continental crust. It is one of the hardest natural stones, making it the preferred material for monuments like Mt. Rushmore.
Field identification & locations
Identify by its 'salt and pepper' speckled appearance and high hardness (it will easily scratch glass). Common in riverbeds, glacial deposits, and mountain ranges worldwide.
