BARYTE on WITHERITE

SPECIMEN DESCRIPTION

The texture of this specimen is something only really seen in the Yorkshire Dales. It is well-known for Baryte (barium sulphate) to replace Witherite (barium carbonate), especially when sulphides oxidize, producing acidic conditions where carbonates are dissolved and sulphates form in their place. However, the extensive replacement of banded, nodular Witherite with finely crystallized Baryte appears to be restricted to the Dales. This small cabinet specimen from Danby Level in Arkengarthdale shows secondary supergene Baryte taking on and preserving the layered form of Witherite, but with a consequent change in volume allowing the Baryte to developed as small crystals following the outline of the Witherite layers. An unusual and really well presented example of this rare type of replacement.