Copper

Habit
Copper crystals are very rare. Foote (176) describes minute distorted dodecahedrons, and in the collection of Mr. Schuster are two crystals a quarter of an inch in diameter—one a cube modified by the dodecahedron and a flat tetrahedron, the other a dodecahedron modified by the octahedron. These crystals are but thin shells of copper enclosing cores of granular datolite, and they are embedded in a matrix of massive axinite, datolite, and willemite.

Occurrence
Commonly the copper is down in irregular hackly masses, films, wires, or spangles, generally associated with one or more of the minerals willemite, hancockite, roeblingite, datolite, axinite, cyprine, garnet, caswellite, or barite. It was first known from the Parker shaft and was apparently fairly common there, some pieces weighing a pound having been found in the crushed ore after it had passed through the rolls.

Copper was first noted by Wolff (174) in specimens taken from a depth of about 800 feet in the Parker shaft. He regarded it a surely later than the zinc ore and as having been introduced along shear zones by solutions. In some specimens, however, it is embedded in clear crystalline willemite and must have been contemporaneous with that mineral. The associated minerals indicate a pneumatolytic origin and a derivation from the intrusive pegmatite. It has also been found in thin veins containing hodgkinsonite, with barylite, and with the recently discovered arsenate hedyphane.


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	This page created: August 12, 2006 5:55 PM