Bournonite (“cogwheels”) black and very well-crystallized

and very well-crystallized

which is typically what you would expect out of a metamorphic contact like this

There is an interesting white "vein" of Microcline running through the center of one of the Amazonite crystals

excellent quality

Specimen # CUAUS72011

Bournonite (“cogwheels”) black and very well-crystallizedA hard to find "cogwheel" group of sharp, thick, blocky modified twinned crystals of Bournonite with excellent metallic luster. The piece displays well from a few angles. The stacked appearance of the crystals, combined with the bright luster, makes this one of the more eye catching smaller Bournonites available. Specimen # BOL711B23