- Class 2. Earths.
- Order 2. Aggregate.
Fire-stone commonly so called by all the masons, especially in the neighbourhood of London, is very little known to mineralogists, nor do I know it to be described in any scientific work. Its peculiarities and particularly useful qualities render it of great consequence; and although it is not rare, yet we know of only one place where it is to be found of the most perfect quality: it forms a stratum in the quarries in the neighbourhood of Godstone, where there is some attention paid to the proper quarrying and seasoning of it. It is truly a domestic stone, being the only one used , when it can be got, for the insides of chimneys, &c. nearest the stoves or fire. It is somewhat granular, of a softish texture, (rubs off with a touch of the linger,) being a mixture of Lime (about 22 percent.), Sand, grains of dark green Chlorite or Talc, and shining particles of Mica, with a little Alumine coloured grayish with a trace of Iron; but this is only the most chosen sort: sometimes it may be impure, with Pyrites and Flinty masses; the former most commonly in the stone above the best bed or stratum, and the latter generally underneath. It is occasionally used in building without such particular choice, but, being soft, allows of Confervæ, Byssi, &c. growing on it, which soon discolour it if in a damp situation. The Fire-stone is used by the notable housewife for cleaning and whitening Portland Stone steps and platforms, and occasionally by masons for practice in carving; but Burrell is more generally used for the latter purpose. It is somewhat related to the Mulatto-stone of Ireland and that of Cambridge.
Sir Robert Pocklington broke a cast of a shell from a piece in one of the older quarries in Surry, in the neighbourhood of Meestham. There seems but little difference in some of the Limestone of Maidstone in Kent, which they there call Cork; but it is more hard and compact than the Fire-stone, and is used for flooring in malthouses. Is its qualification in this particular owing to the Chlorite or Talc, as it has little or no Mica in it? It is figured in the form of a Trochus.
- * It must not be confounded with common Flints, which are sometimes called Fire-stones, Pierres à Feu, &c.