Journal of Geology, Vol. XVIII, No. 6 



Plate II 



iHiTrt-tTtT«^^^-7TTT'r<t7" rrri- rr r 1 i i ' w i n t j rrr ' i ff r 



(a) Twin of calcite produced by compression 



{b) Fluorite crystal before and after compression 



(c) Nickel steel disiv penetrated by the edge of a crystal of fluorite 



