An experiment conducted by
Josiah Wedgwood, led to it being used in his '
Jasper ware'; the mineral had previously been considered as worthless. Witherite crystallizes in the
orthorhombic system. The
crystals are invariably twinned together in groups of three, giving rise to pseudo-hexagonal forms somewhat resembling bipyramidal crystals of
quartz, the faces are usually rough and striated horizontally. It occurs in veins of
lead ore at
Hexham in
Northumberland,
Alston in
Cumbria,
Anglezarke, near
Chorley in
Lancashire and a few other localities. Witherite is readily altered to barium
sulfate by the action of water containing
calcium sulfate in solution and crystals are therefore frequently encrusted with
barytes. It is the chief source of barium
salts and is mined in considerable amounts in Northumberland. It is used for the preparation of rat poison, in the manufacture of
glass and
porcelain, and formerly for refining
sugar. It is also used for controlling the
chromate to
sulfate ratio in
chromium electroplating baths. Witherite-216507.jpg|Two sharp pseudohexagonal crystals of witherite on calcite from
Hardin County, Illinois (size: 6.4 × 5.4 × 3.4 cm) Witherite-65711.jpg|Witherite crystal from the Cave-in-Rock Sub-District, Illinois – Kentucky Fluorspar District, Hardin County, Illinois ==See also==