Talc

Highley, D.E.. 1974 Talc. London, UK, HMSO, 30pp. (Mineral Dossier No. 10)

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Abstract/Summary

Talc is a hydrated magnesium silicate with the formula Mg3 Si4 01o(OH)2 . The mineral is extremely soft (it is the standard for hardness 1 on Mohs'scale) and has a characteristic soapy feel. Commercial grades of talc range in colour from white-to grey and may contain varying proportions of associated minerals, the most common of which are magnesite and chlorite. Talc deposits occur in a metamorphic environment associated with either ultrabasic rocks or dolomitic limestones. In the United Kingdom, talc is almost entirely confined to metamorphosed ultrabasic rocks which have undergone hydrothermal alteration; its occurrence, therefore, is largely restricted to the Highlands and Islands of Scotland, although it also occurs in Cornwall and Anglesey. Deposits of talc are- found mainly in the Shetland Islands, in particular on the island of Unst, where the only talc producer of any significance in the United Kingdom is situated. A talc-magnesite deposit occurs at Cunningsburgh on the Mainland of Shetland and other talc deposits are known at Portsoy, Banffshire; Corrycharmaig, Perthshire; Glenelg, Rossshire and in the Innellan and Toward district of Argyllshire, some of which have been worked in the past. At Polyphant near Launceston, Cornwall an altered ultrabasic rock, known as 'Polyphant Stone',. consisting mainly of talc and ~hlorite, is worked from time to time. Dereliction caused by talc exploitation in the United Kingdom is negligible because of the small size of the operations. Industrially, talc is valued for its softness, smoothness, dry lubricating properties, whiteness, chemical inertness and foliated structure, among other properties. Its most important and best known applications are in the cosmetics and pharmaceutical industries although its use as a filler and extender in paints is also important. The mineral is also used in the manufacture of certain ceramics, as a filler and dusting agent in the roofing felt, rubber and plastics industries and in the manufacture of fertilizers and insecticides, as well as in numerous other applications. Commercial grades of talc range in quality from the high purity, white, cosmetic grades to greycoloured, low-grade tales often containing in excess of 50 per cent impurities. Prices generally range between £12 and £55 per tonne depending on grade. The United Kingdom is, by world standards, a very minor producer of talc, production in recent years being only about 10,000 to 12,000 tonnes, although in 1973 production increased to 20,333 tonnes. The United Kingdom is a significant importer of talc, Norway, France, Italy, and China being the main sources of supply; in 1973 imports amounted to 63,283 tonnes valued at £2,266,690. Exports, consisting of imported material further processed, are small and amounted to 2,044 tonnes in 1973. Almost all the United Kingdom output of talc is produced by Alexander Sandison and Sons Limited, from operations near Baltasound on Unst in the Shetlands. The mineral, which is produced by open cast quarrying, is relatively low-grade, containing only about 45 per cent talc, the main accessory mineral being magnesite. The whole of the production is sold to Yate Mills Limited, a member of the English Orina Clays Group, for milling at their works at Yate near Bristol. Small quantities of the talcose Polyphant Stone are produced at Polyphant in Cornwall by Clarborough Products Limited.

Item Type:	Publication - Report
Programmes:	BGS Programmes > Economic Minerals
Funders/Sponsors:	Institute of Geological Sciences
Additional Keywords:	Mineral, Talc
NORA Subject Terms:	Earth Sciences
Date made live:	25 Jul 2025 16:58 +0 (UTC)
URI:	https://nora.nerc.ac.uk/id/eprint/539900

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