Granite Cobble/Pebble

Hardness: 6-7 (Mohs scale); Color: Typically light-colored (white, pink, gray) with dark mineral grains. The specimen appears to be a black and white/light tan speckled variant; Luster: Vitreous to dull; Crystal structure: Phaneritic (coarse-grained), interlocking crystals; Cleavage: Generally poor, breaks by fracture; Specific Gravity: 2.6 to 2.7 g/cm³

Granite is a common type of felsic intrusive igneous rock that is granular and phaneritic in texture. It forms from the slow crystallization of magma below Earth's surface. Its formation requires significant pressure and high temperatures, indicative of deep geological processes. Most granites formed during periods of continental collision and mountain building. It is primarily found in the continental crust, often as large batholiths.

Industry: Widely used as crushed stone, dimension stone for buildings, monuments, and curbing. Also used as aggregate in concrete and asphalt. Construction: Countertops, flooring, wall cladding, and paving. Jewelry: Not typically used for jewelry, but polished granite can be used for decorative items.

Granite is one of the most abundant igneous rocks in the Earth's continental crust. It is a key component of mountain ranges and forms the core of many continents. The term 'granite' comes from the Latin 'granum', meaning 'grain', in reference to its coarse-grained structure. Its durability and aesthetic appeal have made it a favored material for centuries.

Identification in the field: Look for its speckled appearance, typically with interlocking, visible mineral grains of contrasting colors. It feels hard and rough on broken surfaces, but river-worn or glacially-smoothed pebbles like the one shown will feel smooth. Light to medium color is typical. Common locations: Found globally in continental crust, especially in areas of past or present mountain building. Examples include the Sierra Nevada Batholith (USA), Scottish Highlands, and parts of Scandinavia. Tips for collectors: Granite pebbles are common in riverbeds, glacial deposits, and coastal areas where larger granite formations have eroded. Look for its characteristic mottled appearance and hardness.