362 On-Primary Ores of- Iron. 



fmall fize, none of them meafuring more than 

 upon the bafe. 



The various {hades of garnet, yellow, and green coloured 

 cryftals, when found of a large fize, have generally affumed 

 the form of a prifm, a cube, or a parallelopipedon with 

 flattened edges : none of thefe, however, poffefs the tranfpa- 

 rency of the pure quartzofe cryftal. The whole of thele forms 

 are found in chafms in the large mafi'es of fplinty ore : when 

 the cavity is broken up, the groups of cryftals are found 

 occupying all its fides, and projecting their tops to each 

 other. Not unfrequently clufters of cryftals are found im- 

 bedded in a thin ftratum of beautifully cryftallifed prifmalic 

 iron-ore, obedient to the magnet, and poffefled of the mod 

 fplendid dazzling colours. 



The Lancafhire ore is compofed of fmaller nlaffes, fofter, 

 and of a more greafy appearance ; there are, however, in it 

 all the former variety of cryftals, though of a fmaller fize. 

 The quality of this ore is alfo much preferred in the blaft fur- 

 nace, whether in the procefs with pit-coal coaks, or with 

 the charcoal of wood. This partiality is owing to the mix- 

 tures in it being more favourable to the exiftence of carbon 

 in the blaft furnace : clay, and not unfrequently calcareous 

 cryftals, are found in this ore; whereas the earthy mixture 

 of the Cumberland ore is chiefly filieeous, with a fmall por- 

 tion of fulphur. Both of thefe ores, in the kidney variety, 

 contain fine fpecimens of foible plumbago. 



In feveral places in Scotland iron ores have been difco- 

 vered refembling in point of appearance thofe of Cum- 

 berland and Lancafhire : fome individual pieces as rich in 

 iron, but the average quality, as to contents in iron, infe- 

 rior. The quantity hitherto found lias been fo fmall, and its 

 locality fo infulated, that it has never been, to the manu- 

 faeluver, an object of attention, nor of farther fearch to the 

 proprietor. In the Weft Highlands fome tranfient veins 

 have been found, but their irregularity of diipofition has 



hitherto 



