Silicon

Physical Properties

Hardness: 6.5-7 (Mohs); Color: Dark gray to bluish-black with a metallic silver surface; Luster: Sub-metallic to metallic; Crystal structure: Diamond cubic; Cleavage: Octahedral; Specific gravity: 2.33

Formation & Geological History

Silicon is rarely found in its pure native state in nature; it usually occurs as silica or silicates. Industrial silicon (like the specimen shown) is produced by heating silica with carbon in an electric arc furnace. It is fundamental to the formation of most igneous rocks.

Uses & Applications

Primary component in semiconductors, microchips, and electronics. Used in solar panels, the production of aluminum alloys, and the creation of silicones for lubricants and sealants.

Geological Facts

Silicon is the second most abundant element in the Earth's crust by mass (about 28%), surpassed only by oxygen. While essential to geology, 'native' silicon (natural pure silicon) is extremely rare and only found in specific volcanic environments or as inclusions.

Field Identification & Locations

Identify by its light weight (low density) compared to silver or lead, its very high hardness which can scratch glass, and its distinct brittle, glass-like fracture on fresh surfaces. Found globally in quartz and silicate deposits.

Identified on: 4/19/2026

Mode: Standard