Granite

Hardness: 6-7 on Mohs scale. Color: Typically speckled (salt-and-pepper) with dominant pink, white, or grey feldspar; translucent quartz and black mica/hornblende. Luster: Vitreous to dull. Crystal structure: Phaneritic (coarse-grained), interlocking crystals. Cleavage: Good in feldspar and mica, none in quartz. Specific gravity: 2.65-2.75.

Formed from the slow crystallization of magma below Earth's surface (intrusive igneous rock). It typically forms at considerable depths in continental crust and is exposed at the surface after uplift and erosion. Geological age: Can range from Precambrian to Cenozoic.

Industry: Countertops, flooring, paving, building facades, monuments, road aggregate. Construction: Durable and aesthetically pleasing building material. Uses in jewelry/collecting: Used as ornamental stone for its beauty and durability; not typically considered a gemstone itself but polishes well.

Granite is the most abundant intrusive igneous rock in the Earth's continental crust. It forms the core of many mountain ranges. Its name comes from the Latin word 'granum', meaning 'grain', in reference to its coarse-grained structure.

To identify in the field: Look for its speckled appearance with interlocking, visible mineral grains. The presence of at least 20% quartz, along with feldspar and mica/hornblende, is key. It is a very hard rock, resisting scratching. Common locations: Found globally in mountainous regions, shield areas, and continental cratons. Major occurrences include the Sierra Nevada in California, Appalachians in North America, and vast areas of the Scandinavian Peninsula and Russia. Tips for collectors: Look for fresh exposures in road cuts, quarries, and glaciated areas where granite boulders are common. A hand lens is useful to identify individual mineral grains.