Copper (twinned) - image 1

Copper (twinned)

T

The Mineralogical Museum, University of Delaware
0 for sale
Copper (twinned), 16.5 cm, from the Keweenaw Peninsula, Michigan.

Product details

Species
CopperAbout Copper →
SizeLarge Cabinet
Dimensions16.5 cm
Added on02/13/2026
Locality
USA, Michigan, Keweenaw PeninsulaRegional guide →
Publications
  • Mineralogical Record Mineral Collection University Of Delaware page 53

Learn more

Copper
Mineral guide
Learn about Copper
native copper with spinel-twinned crystals and arborescences; notable from Lake Superior, Itauz, Dongchuan, Corocoro, prized for color and localities.
Copper
Regional guide
Copper from Keweenaw Peninsula, Michigan, USA
The Keweenaw Peninsula is the classic native-copper locality: a place where copper was not merely an ore mineral locked in sulfides, but the metal itself—dense, malleable, and often sculptural—precipitated as copper, Cu, in billion-year-old volcanic rocks. For collectors, “Keweenaw copper” is a category unto itself. It can appear as wiry arborescent sprays, thick hackly sheets, crystal groups with sharp metallic faces, rounded glacial float nuggets, massive vein copper, copper-filled amygdules in basalt, and copper in conglomerate where the metal laces between volcanic pebbles.