igneous
Granite Cobble
Granite (Phaneritic igneous rock)
Hardness: 6-7 Mohs; Color: Mottled gray, pink, and black; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarsegrained visible crystals); Specific gravity: 2.63 to 2.75
- Hardness
- 6-7 Mohs
- Color
- Mottled gray, pink, and black
- Luster
- Vitreous to dull
Identified More igneous →
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Physical properties
Hardness: 6-7 Mohs; Color: Mottled gray, pink, and black; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarsegrained visible crystals); Specific gravity: 2.63 to 2.75
Formation & geological history
Formed by the slow crystallization of magma below the Earth's surface (plutonic). This specific specimen has been Rounded by water erosion in a river or stream environment. Geological age ranges from Precambrian to Cenozoic.
Uses & applications
Used in construction as dimension stone, countertops, paving, and as aggregate. Polished specimens are used for decorative landscaping and aquarium decor.
Geological facts
Granite is the most common rock found in the Earth's continental crust. It is primarily composed of quartz and feldspar, which give it its durability and light colors.
Field identification & locations
Identify in the field by its 'salt and pepper' appearance and visible, interlocking mineral grains. Commonly found in riverbeds, glacial moraines, and mountain ranges. It is resistant to weathering.
