Tarnishes green, sometimes blue or black. Crystals are usually cubic or dodecahedral .
Octahedral crystals do occur, but are very rare.
Also occurs as flattened crystals, scales , dendrites , and wires . Other Names Native Copper Varieties Copper Bloom - Copper with green and blue tarnish stains speckled throughout. Native copper is found only in small quantities throughout the world, but there are a few areas that are rich in findings, such as the Keweenaw Peninsula in Michigan. Well crystallized specimens are not common, and are very much sought after. Uses Native Copper was the only source of copper until the turn of the century, when extraction methods were improved.