igneous

Granite

Phaneritic Felsic Igneous Rock

Hardness: 6-7 Mohs; Color: Salt and pepper (gray, white, black); Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained, visible crystals); Specific gravity: 2.63 to 2.75

Hardness: 6-7 Mohs
Color: Salt and pepper (gray, white, black)
Luster: Vitreous to dull

Identified May 10, 2026More igneous →

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Physical properties

Hardness: 6-7 Mohs; Color: Salt and pepper (gray, white, black); Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained, visible crystals); Specific gravity: 2.63 to 2.75

Formation & geological history

Formed from the slow cooling of silica-rich magma deep underground (plutonic). Typically associated with continental crust and mountain-building events over millions of years.

Uses & applications

Widely used in construction, countertops, flooring, monuments, and as crushed stone for road base and railroad ballast.

Geological facts

Granite makes up a large portion of the Earth's continental crust. It is extremely durable and resistant to acid rain, which is why it is preferred for outdoor monuments and tombstones.

Field identification & locations

Identify by its interlocking crystals of quartz, feldspar, and mica. It is common in mountain ranges and continental shields. Look for a speckled appearance and high hardness (will scratch glass).

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Blue Apatite

Fluorapatite (Ca5(PO4)3F)

mineral

Dark Igneous Rock (Likely Basalt or Diabase)

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.

Igneous