- Prehnite with Copper (sharp crystals)
- Iroquois Mine, Mohawk, Keweenaw Co., Michigan, USA
- Miniature, 4.6 x 4.2 x 2.1 cm
- Ex. Charlie Key
Here is a rarity both in species and association from the copper district of the Upper Peninsula of Michigan! A few dozen, 1 to 2.5 mm, well formed Copper crystals dot the surface of some low-profile Prehnite botryoids, themselves growing on Prehnite. Under the microscope, the sharp copper crystals are complex and appear to display tetrahexahedral and/or dodecahedral forms ; and there is one isolated wire of Copper that appears to be a very elongated cube 8 mm in total length that has almost a right angle bend to it! The Prehnite botryoids are a light to medium mint-green and can be seen to be composed of very tight, arcuate clusters of crystals with a satin luster. There is one off to one side that measures 2 cm across that has good color and translucency. The bottom of the piece has small patches of altered basalt matrix. This a great and very unusual Prehnite-Copper combo from the Copper Country of Michigan! While Charlie has not provided a mine name, it is a dead ringer to a specimen posted by a well known Copper Country expert and speaker (including as a past speaker at our own Dallas Symposium), Paul Brandeis: https://www.mindat.org/photo-279070.html. I feel confident about the mine attribution in this case, because of the comparable online.