Native Copper in Basalt

Physical Properties

Hardness: 2.5-3 (copper), 5-6 (basalt); Color: Reddish-brown, metallic orange-red, with dark grey-green matrix; Luster: Metallic (copper), Dull (matrix); Crystal Structure: Isometric; Cleavage: None; Specific Gravity: 8.9 (copper pieces).

Formation & Geological History

Formed through hydrothermal precipitation within the vesicles and fractures of volcanic basalt, often occurring as secondary mineralization. Historically associated with ancient Precambrian rift zones, such as the Midcontinent Rift System (~1.1 billion years old).

Uses & Applications

Major industrial source of electrical wiring, plumbing, and electronics. High-grade specimens are prized for mineral collections and lapidary arts.

Geological Facts

The Keweenaw Peninsula in Michigan is world-famous for producing massive 'float copper' boulders and amygdaloidal copper specimens similar to this one. It was used by indigenous peoples for thousands of years to create tools and ornaments.

Field Identification & Locations

Identify in the field by checking for high density/heaviness, reddish oxidation colors, and malleability (copper will scratch and bend rather than shatter like brittle minerals). Found in volcanic regions with copper mineralization.

Identified on: 4/20/2026

Mode: Standard