These native copper crystals are from the Northwestern Mine in Central, Keweenaw County, Michigan, USA. This mine operated in the mid 1800’s for the recovery of copper. It was later incorporated into the Central Mine. It contained 12 different minerals including copper. This piece is made up of fairly large well defined crystals. The patina varies from a light malachite coating to a burnished red color. It measures approximately 3 1/8 x 2 1/2 x 7/16 inches or 79 x 65 x 10 mm.