Copper

Unknown Owner

Very aesthetic cluster of sharp well defined crystals of native copper, the largest measuring to 0.7 cm in size. From the collection of Don and Gloria Olson, in excellent condition all around.The Cliff Mine in Keweenaw County, Michigan, was the first successful large scale copper mine in the Keweenaw Peninsula and began operations in 1845. It worked rich native copper deposits in fissure veins cutting basalt of the Portage Lake Lava Series and quickly became one of the most productive mines in the region during the mid 19th century. The mine was developed with deep shafts and extensive underground workings that followed the copper bearing veins. Although production declined later in the century and the mine eventually closed, the Cliff Mine played a key role in establishing the Michigan copper mining industry.