Copper Nugget

Physical Properties

Hardness: 2.5-3.0 Mohs; Color: Copper-red to dull brown with green/black tarnish; Luster: Metallic; Crystal Structure: Isometric; Specific Gravity: 8.9; highly malleable and ductile.

Formation & Geological History

Native copper forms in the oxidized zones of copper deposits or through hydrothermal activity where copper-bearing fluids permeate basaltic lava flows or sedimentary rocks. This specimen shows typical rounded morphology from alluvial transport or oxidation.

Uses & Applications

Primary use in electrical wiring, electronics, plumbing, and industrial alloys like brass and bronze. Aesthetic copper nuggets are valued for lapidary work, jewelry, and mineral collections.

Geological Facts

Native copper is one of the few metals that occurs in nature in a directly usable metallic form. The largest deposits historically were the Keweenaw Peninsula in Michigan, which produced massive nuggets weighing several tons.

Field Identification & Locations

Identify by high density, metallic copper-red color when scratched, and malleability (it bends rather than breaks). Commonly found in the Lake Superior region (USA), Arizona, and Chile. Conduct a streak test; it should leave a shiny metallic copper streak.

Identified on: 4/30/2026

Mode: Standard