igneous

Granite Pebble

Granite (Phaneritic Igneous Rock)

Hardness: 6-7 (Mohs scale); Color: White/Light grey matrix with black speckles; Luster: Dull to vitreous; Crystal structure: Phaneritic (visible crystals); Cleavage: None (subconchoidal fracture); Specific gravity: 2.63-2.75

Hardness: 6-7 (Mohs scale)
Color: White/Light grey matrix with black speckles
Luster: Dull to vitreous

Identified May 26, 2026More igneous →

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Physical properties

Formation & geological history

Formed from the slow cooling of silica-rich magma deep beneath the Earth's surface (plutonic formation). This specimen shows rounded edges indicating high-energy water erosion, likely a river or beach pebble.

Uses & applications

Used primarily as decorative landscaping stones, aquarium gravel, or as an educational geological sample. In bulk, crushed granite is used for road base and construction.

Geological facts

Granite is the primary rock that makes up the Earth's continental crust. Specimens like this often contain Quartz (white), Feldspar (cream), and Biotite or Hornblende (black flecks).

Field identification & locations

Identify by its 'salt and pepper' appearance and hardness (it will scratch glass). Commonly found in riverbeds, glacial tills, and coastal beaches globally. Collectors look for unique wear patterns or mineral inclusions.

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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