Copper Firebrick Cabochon - approx. 10 x 10 x 3.9 mm

Copper Firebrick Cabochon - approx. 10 x 10 x 3.9 mm

Reclaimed copper infused Firebrick from a copper mine/smelter in Michigan, USA, unbacked

Coin for size reference: US Dime (similar size as UK 5p)