Suredaite

We don't see too many minerals from Argentina but here is a rare one from la Mina Pirquitas. The top of this matrix is covered with tiny clusters of a mica-like mineral and sharp, spear-like surdaite crystals, to 1mm poke out of the micaceous mineral everywhere. Surdaite is a very rare lead-tin sulphide and this is the type locality. I've never seen one for sale before!