Massive Talc, Potstone, or Lapis-ollaris
- Div. 1. Crystallized.
- Potstone. Kirw. 1. 155.
- Lapis-ollaris. Waller. Bab. Min. 39.
- Talc ollaire. Haüy, 3. 257.
- Topfstein. Emmerl. 3. 282.
Although this is not a rare substance in countries where Serpentine Hocks occur, it is nevertheless often too unequal in its nature to answer the purpose of turning into pots. In Scotland it is abundant; and the Duke of Argyle’s house at Inverary is said to be built of it; yet it is but little known. I have seen sets of lea equipage, and I have a tankard made of it from abroad; and in Saxony it seems that hundreds of people are employed in manufacturing it. The usual kind abounds with Talc, and is of an even and close texture; but that which is used varies much, and more or less approaches Talcose Schist and Serpentine. Some of the cups which I have from Italy seem to be a Talcose Schist, with Garnets of such an equal state of hardness, that the whole turned equally well.
The upper figure is a representation of a specimen from Brcadalbane of the common texture; but the fibres are rather more than usually varied in their direction, so as to make it nearly free to cut or turn to any form.
The tower figure is a more Schistose variety, from the same place, commonly called Schistose Potstone. The different kind of Potstones vary much in colour.
I have figured this substance rather as a mineral than as a specimen of such as is turned in the lathe, although it would answer the purpose pretty well in a certain proportion. Its stellated formation is rather rare; I have not, however, represented that variety: but, from what has been said, it may be readily understood that there may be numerous varieties; and those of the most equal texture throughout are to be preferred. They are generally somewhat porous, and sometimes do not hold water better than the vases, &c., made in Derbyshire and other Fluor countries.
The inhabitants of New Caledonia occasionally use a sort of Potstone Steatite to assist them in the place of food when it is scarce.
I wonder that there are no such Potstone manufactories in Great Britain as those in Saxony; for I think there is but little doubt of procuring the Stone as likely to answer this purpose as the foreign sort. Perhaps, however, there would not be a sale for them.