igneous

Granite Pebble

Granite (composed mainly of Quartz, Feldspar, and Mica)

Hardness: 6-7 on Mohs scale; Color: Salt and pepper (white/grey with dark flecks); Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Specific gravity: 2.6-2.7

Hardness: 6-7 on Mohs scale
Color: Salt and pepper (white/grey with dark flecks)
Luster: Vitreous to dull

Identified May 23, 2026More igneous →

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Physical properties

Hardness: 6-7 on Mohs scale; Color: Salt and pepper (white/grey with dark flecks); Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained); Specific gravity: 2.6-2.7

Formation & geological history

Formed through the slow crystallization of magma below Earth's surface. This specimen has been rounded through weathering and erosional transport, likely by water.

Uses & applications

Crushed granite is used in construction as aggregate for roads and concrete. Large slabs are used for countertops and monuments. Tumbled pebbles are common in landscaping.

Geological facts

Granite makes up a large portion of the Earth's continental crust. Its name comes from the Latin 'granum', meaning a grain, in reference to its coarse-grained structure.

Field identification & locations

Identify by its speckled 'salt and pepper' appearance and its ability to scratch glass. Commonly found in riverbeds, glacial deposits, and mountain ranges. It is an extremely common rock globally.

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Basalt (extrusive igneous rock) or Diabase (intrusive igneous rock - also known as Dolerite), largely composed of plagioclase feldspar, pyroxene (augite), and sometimes olivine and amphibole. Exact mineralogy would require thin section analysis.

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Magnetite

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Blue Apatite

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Magnetite

Magnetite (Fe3O4)

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