This is a fascinating old Michigan specimen, to me. What you have is a very large specimen of datolite, infused with copper so that it is actually tinted a coppery color - and, surrounded by copper-rich ore. Datolites have become so sought-after and hard to obtain, for whatever reason. Though they do not compete in aesthetics with a fine crystal specimen, there is just some aura about them these days that gets collectors excited - perhaps their old Michigan connotations. This is certainly a very unusual and exciting one, with its copper assocation! Ex. Hauck COllection. 9.5 x 8.0 x 5.9cm