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.