Silver in Calcite, B Shaft, Old Copper Falls Vein, Copper Falls Company, Lake Superior Copper District, Keweenaw County, Michigan Miniature 2 x 3 x 4 cm $350. Online 7/12
NSMW10860
Native silver enclosed in calcite with associated microcline and basalt matrix. The contact along the matrix is smooth and linear and shows the silver was emplaced along a small narrow veinlet as an offshoot of the main Copper Falls Fissure. B Shaft was one of 4 sunk on the fissure here in the mid-1840s and worked for only a couple of years before activity was transferred to the Petherick and Owl Creek Fissures. The Old Copper Falls Mine, as it came to be called, was one of the very first operations in the district. Old company reports reveal an interesting fact , namely, silver was richly mineralized when the main vein pinched. Moreover, the silver was strongly associated with chlorite and calcite. This gave me a head's-up when field collecting in the old poor rock piles back in the mid-1980s and when my detector rang out a song on chlorite-rich thin slabs of metal-bearing vein material it was especially exciting. I found this c. 1984 and left it in the original condition without acid cleaning to show the association. It was one of the nicest and largest pieces I collected. No faults.