chalcopyrite - larger student specimens from a skarn in Mexico's Sierra Madre - Unit of 5 student specimens Peru and the Alps were

Peru and the Alps were the only sources of pink fluorite at astronomical prices

unescaped gases form voids in the otherwise solid flow

" The contrast between upperside and  underside is well illustrated here

It has a similar structure to minerals in the serpentine group

which has a silica content of 50 to 85%

chalcopyrite - larger student specimens from a skarn in Mexico's Sierra Madre - Unit of 5 student specimens Peru and the Alps werechalcopyrite CuFeS2 El Bolvar Mine Piedras Verdes District, municipality of Uruque, Chihuahua, Mexico The Bolvar Mine is an historic underground copper zinc mine, working a skarn formed during contact metamorphism of carbonate bearing rocks. Located in an area of northwestern Mexico's Sierra Madre that has been mined and prospected for polymetallic copper zinc lead silver and gold deposits since the Spanish colonial period, it produced around three