Sunday, May 16, 2010

Unst Talc

If you have ever wondered where talcum powder comes dig it up from Unst. Well not the sort you put on a baby's bum, but talc nevertheless. Cross Geo Talc Quarry near Clibberswick is one of the few commercial talc (magnesium silicate), quarrying operations in the UK and is currently managed by Sandisons (Unst) Ltd. Large quantities of Talc deposits are present on Unst and on Fetlar, and also just south of Cunningsburgh (south Mainland) at Catpund. Queyhouse Quarry on Unst (near Loch of Cliff) was also used for talc extraction from the mid-1940's but this site has now been abandoned. Talc extraction on Fetlar ceased in 1914 and although an assessment of commercial extraction was undertaken at Catpund it has never been developed.

Cross Geo Talc Quarry with a pile of quarried talc awaiting collection.

Talc is formed when hydrothermal influences are applied to Serpentine which breaks down to give talc and brucite and this combination is found on Unst and Fetlar. If carbon dioxide is present the serpentine breaks down to give talc and magnecite instead of brucite. The talc seam at Catpund is combined with magnecite.

The talc from Cross Geo gives an off-white to brown powder when processed and is suitable for industrial use where colour is not important. These applications include kiln furniture manufacture, ceramics, agriculture, roofing, some coating applications and the manufacture of plastics. As it is completely inert it is also used in the formulation of fertiliser and animal feed to enhance the flow or fluidity of the product.

The talc from Cross Geo Quarry is simply dug up and tipped into lorries where it is transported to the Baltasound pier with no further processing. A large walled area at the base of the pier contains the talc until enough is gathered to ship it out.

Talc on the Baltasound pier.

1 comment:

  1. Was at Catspund the other week and found a few nice quality bits of soap stone, to small do do much with but lovely none the less.


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