The Corta Brunita (open pit), in Murcia, is a classic of Spanish mining and mineralogy. This sample shows various globular aggregates of cronstedtite, formed by small crystals with triangular terminal faces. They are disposed on a matrix with smithsonite.

Cronstedtite is a rare iron silicate of the kaolinite-serpentine group. This is a good representative of the cronstedtite specimens from this classic Spanish mine. It shows a lustrous, black, trigonal crystals forming groups on the matrix. It is a rare oportunity to get good specimens of this species.