Copper (Pipe amygdule), Central Mine, Lake Superior Copper District, Keweenaw County, Michigan Medium cabinet 0.9. 1.3 x 16.0 cm $200. Online 6/6
Pipe amygdules form in the last stages of lava cooling as gasses escape or are trapped within the flow. In this case, the lava was stationary and the gas bubble basically vertical. Following cooling, copper-rich solutions filled the void and this pipe amygdule was the result. This piece is exceedingly long (the longest I have ever seen in fact) and exceptionally nice for display. Note the offset near the center as the result of a fracture within the basalt. William A.N. Severance Collection #97.60. No faults.