Excellent well-defined single spinel twin crystal of Copper that is an amazing 6.7 cm long. The modified Copper cubes growing the length of the specimen are attractive and sharp, and the copper has an excellent patina. Spinel twin Coppers this long are far and few between from African locales. This old copper specimen is from the Stan Korowski collection who originally brought out many of the famous Zambian minerals and wrote about them extensively in the Min. Rec and other journals years ago.