Granite

Physical Properties

Hardness: 6-7 on Mohs scale; Color: Salt-and-pepper appearance with white/grey, black, and pink/orange hues; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained visible crystals); Cleavage: Indistinct on the rock, though feldspar crystals within may show perfect cleavage; Specific Gravity: 2.63 to 2.75

Formation & Geological History

Formed through the slow crystallization of magma below Earth's surface. It is a plutonic rock that cools over thousands to millions of years, allowing large crystals to grow. Most granites date from the Precambrian to Cenozoic eras.

Uses & Applications

Extensively used in construction for countertops, floor tiles, paving stones, curbing, and monuments. High-quality specimens with unique patterns or colors are popular among lapidary enthusiasts and mineral collectors.

Geological Facts

Granite makes up the majority of the Earth's continental crust. Unlike oceanic crust which is primarily basalt, continental crust is thick and 'buoyant' due to its granitic composition. Some of the oldest known rocks on Earth are granites.

Field Identification & Locations

Identify in the field by its speckled 'salt and pepper' look where individual mineral grains (Quartz, Feldspar, Mica) are easily distinguishable with the naked eye. It is extremely common in mountain ranges and continental shields. Collectors look for large, well-defined Accessory minerals like tourmaline or garnet within the matrix.

Identified on: 4/25/2026

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