Calcite 
 
Locality: Tonglushan Mine, Hubei, China

Size: 83 mm x 54 mm
 
A beautiful blade-like specimen, on the one side it is reddish-brown and the other side more clear. A lovely specimen from this mine, known to produce reddish coloured calcites.
 
Calcite is a carbonate mineral and a polymorph of Aragonite. It is extremely variable in colour, ranging from clear, white, yellow, orange, blue, pink, red, brown, green, black and grey.