Size  5cm x 4cm
These pyrite crystals are the best in the world as far as I am concerned. A perfect cubic pyrite crystal 20mm x 20mm  sits atop a piece of matrix. The photos don't really show how mirror shiny these things are. Writing can be read in the reflection from a crystal face of the pyrite crystal. A showy pyrite crystal still in its original matrix. 
For the sceptics out there, these crystals are completely natural and have not been cut or polished in any way. The white matrix has been cleaned away from the pyrite crystal to expose the crystal, but thats it.