On Primary Ores of Iron. g^l 



among ft the Cumberland ores. Thefe at once convey the: 

 idea of the agency of water in their formation : if the internal 

 cavities of fame of the pieces are examined, the proofs mul- 

 tiply and become irrefragable. The chafms in which the cry- 

 ftals are found, and always formed, difplay the procefs of 

 crvftallization in all its various ftages. Cryftals are found in 

 finifli and form proportioned to the ftage of the operation : 

 fome imperfect, and of a clayey confiftencv and colour; others 

 in a more finifhed ftate, hard, but as yet unpolilhcd or dia- 

 phanous : fome are encircled in a flimy membrane, which, 

 when difplaced, difplays the cryftals more or lefs tranfparent 

 as the operation has been more or lefs perfect. I have found 

 cavities in this ore quite filled with water, which in this 

 ftate had been tranfported fome hundred miles; the fides and 

 bottoms of fuch chafms always abounding with a foft mud 

 composed of the fmeft fragments of filex, free from evt-rv 

 touch of afperity. Again, cryftals are found in this ore, which 

 poflefs various degrees of pellucidity ; fome of them very white, 

 \ et dull ; abforbing light, yet tranfmitting little. Others are 

 as clear and tranfparent as the pureft water; their angles 

 frequently decomposing light with all the vivid rfiects of the 

 prifin. Other varieties are lefs diaphanous, but poflefs various 

 tinges of colour, and increafe in opacitv in proportion as the 

 colouring matter is prefent in the cryftal. Some poflefs a gar- 

 net colour more or lefs intenfc, and moft of them tranfmit 

 lefs or more light. 



There is another variety of cryftals among the Cumberland 

 ore, exhibiting a green colour, which is owing to the prefence 

 of an acid. This, like the garnet coloured cryftal, tranfmits 

 light in a greater or letter degree in proportion to the quan- 

 tity of iron prefent. There are alfo various prifmatic crvftals 

 in this ore, of a fmall fizc, which owe their fplcndid and va- 

 riegated luftre to fulphur, and which are eafily tarniflied by 

 the application of heat. Specimens alfo of cryiiallized iron- 

 ore, in the form of razor blades, containing owgen and car- 

 bon, are not uncommon : thefe referable more the liilua ore 



ihnu 



