266 A Geological and Geographical Sketch 



Fullers* Earth is found in most parts of the island, of a 

 light yellowish, brown, and olive-green colour. It occurs 

 massive, fracture earthy, uneven, yields easily to, and receives 

 a polish from, the nail, and falls to pieces in water. 



Volcanic Rock, of a bluish grey colour, passing into pumice ; 

 very common. 



Shale, of a light ochrey yellow, or pinkish brown colour ; 

 fracture large, conchoidal, earthy, and uneven ; dull, opaque, 

 meagre ; adheres firmly to the tongue, yields to the nail. 



Masses of small stones and sand, embedded in iron-clay, 

 and burnt into a kind of red brick. 



Pipe Clay, nearly pure, is found, in large beds, in the 

 crater of Mount Misery. 



Alum and Sulphur, crystallized, are also found in the crater. 



Alumine, full of minute iron pyrites, giving it a bluish 

 black colour, abounds in the crater: these are easily sepa- 

 rated by dissolving the clay in a glass of water. 



Alumine, mixed, more or less, with yellow ochre, is found 

 on many of the hills, particularly to the eastward. 



Greenish brown Lava, very thickly speckled with leucite, 

 is often found to be the interior of a stone that appears dirty 

 red without. 



Vesicular Lava, greyish white, very full of pores and black 

 glittering spots, is very common. 



Leucite, in porous black lava, occurs in large masses. This, 

 as well as some of the other lava rocks, is called '* fire-stone," 

 and is used for building the furnaces of boiling houses, &c., 

 where great heat is required. 



Augite appears in great abundance wherever there is a black 

 soil. It occurs in small broken prismatical crystals, shining, 

 transparent, blackish green, translucent, scratches glass with 

 ease. 



Terrass, of a reddish brown colour, forms the first stratum 

 under the vegetable mould in most parts of the island, parti- 

 cularly the east end. It is used with lime in the composition 

 of mortar. 



Soft white Carbonate of Lime, containing madrepores, 

 composes the principal part of Brimstone Hill. 



Siliceous Sand, consisting of minute particles of dark green, 



