Another gem from my little box of treasures…
Look at the colour zoning on this unusual and rare stone – it is Psilomelane, or Crown of Silver Psilomelane after the Silver Crown Mine in Chihuahua, Mexico where it was found.
While psilomelane has been found in a couple of places in the US, and in small areas of Europe, Africa, and Australia, it is a rare stone.
Psilomelane is a group name for hard, black manganese oxides and this particular stone has a silvery, metallic lustre ‘wood grain’ pattern through the deep black - apparently it is horrible to cut and polish!
It is a stunning stone and with a hardness of 5-6 on the Mohs’ scale would be suitable for making into a pendant or brooch.