Extracts relating to Coat, Sfc. 77 



2. m Post-stone. — This is a freestone of the hardest kind, 

 and next to the limestone with respect to hardness and solidity. 

 It is of a very fine texture ; and when broken appears as if 

 composed of the finest sand. It is commonly found in a homo : 

 geneous mass; though variegated in colour; and, from its 

 hardness, is not liable to injury from being exposed to the 

 weather. Of this kind of stone there are four varieties, which 

 may be distinguished by their colour. The most common is 

 white post, which in appearance is like Portland stone, but 

 considerably harder; it is sometimes variegated with streaks 

 or spots of brown, red, or black. 



Gray post is also very common ; it appears like a mixture of 

 fine black and white sand : it is often variegated with brown 

 and black streaks; the last mentioned appear like small clouds 

 composed of particles of Coal. 



Brown or yellow post is often met with of different degrees 

 of colour ; most commonly of the colour of light ochre or yel- 

 low sand. It is as hard as the rest, and sometimes variegated 

 with white and black streaks. 



Red post is generally of a dull red colour : this is but rarely 

 met with; it is often streaked with white or black. 



All these lie in strata of different thicknesses ; but commonly 

 thicker than any other strata whatever : they are separated 

 from each other, and from other kinds of strata, by partings of 

 coal, sand, or soft matter of different colours which are very 

 distinguishable. 



3. Sand-stone. — This is a freestone of a coarser texture 

 than post, and not so hard ; is so lax as to be easily pervious 

 to water; when broken, is apparently of a coarse sandy sub- 

 stance ; is friable and moulders to sand when exposed to the 

 wind and rain; has frequently white shining spangles in it, 

 and pebbles or other small stones inclosed in its mass. Of 

 this, there are two kinds commonly met with, distinguished by 

 their colours, gray and brown, which are of different shades. 

 lighter or darker in proportion to the mixture of white in them. 

 It is most generally found in strata of considerable thickness, 

 without many secondary partings ; and sometimes, though 

 rarely, it is subdivided into layers as thin as the common gray 

 slate. It has generally sandy or soft partings. 



4. Metal-stone. — This is a tolerably hard stratum, being 

 in point of hardness next to sand -stone ; generally solid, com- 

 pact, of considerable weight, and of an argillaceous substance, 

 containing many nodules or balls of iron ore, and yellow or 

 white pyrites; its partings, or the surfaces of its strata, are 

 hard, polished, and smooth as glass. When broken, it has a 

 dull dusky appearance (though of a fine texture), like hard 

 dried clay mixed with particles of coal. Though hard- in the 



