Granite

Hardness: 6-7 (Mohs), Color: Interspersed light (white, pink, gray) and dark (black, dark green) minerals, Luster: Vitreous to dull, Crystal structure: Granular, phaneritic (visible crystals), Cleavage: Varies per mineral, Specific Gravity: 2.6-2.7 g/cm³

Formed from the slow crystallization of magma below Earth's surface. This intrusive process allows for the formation of large, visible mineral grains. Geological Age: Varies widely, found in all geological ages from Precambrian to Cenozoic, typically associated with continental crust formation and orogenic (mountain-building) events.

Industry: Construction material (countertops, flooring, paving, building facades), monuments, dimension stone. Jewelry: Not typically used as a gemstone, but attractive pieces with unique mineral patterns may be polished for decorative purposes. Collecting Value: Common and widespread, individual specimens are usually of modest collecting value unless they exhibit unusual mineral combinations or features.

Granite is named from the Latin 'granum' for grain, in reference to its coarse-grained structure. It's one of the most abundant intrusive igneous rocks and forms the core of many mountain ranges. The pink color in some granites comes from potassium feldspar.

Identify in the field: Look for its coarse-grained texture and speckled appearance, with clearly visible interlocking crystals of light (quartz, feldspar) and dark (biotite, amphibole) minerals. It is very hard and scratches glass. Common Locations: Found globally in continental crust settings, particularly in mountain belts, shields, and cratons. Major producers include Brazil, China, India, Italy, and the United States (e.g., Vermont, Georgia). Tips for collectors: Granite pebbles can be found in rivers and streams, often smoothed by water erosion. Look for distinct mineral compositions and colors.