Analyjis of an Ore of Iron, &c. 4^7 



{hey are more or lefs removed^ from the metallic ftate. The compafs of this letter wilj 

 not allow me to enumerate them ; and I fliall only therefore obferve, that the eifenmann 

 appears to me to differ from the eifenrahm, merely by a lefs degree of oxydation ; and 

 that the varieties of each are fo many gradations, by which the firft pafTes into the 

 fecond. For example, the eifenmann, in the complete flate, has the luftre and colour 

 of fteel; is not unftiious to the touch, and when fcraped or pulverized, afibrds a grey 

 powder. But other varieties yield a greyifh red, or even a red powder; and, at the 

 fame time certain degrees of unftuofity are to be obferved. Thefe I confider as grada- 

 tions of eifenmann into eifenrahm. Again, fome varieties of the latter poffefs the fleel- 

 grey colour and luftre, and, in the like proportion, become more and more unftuous, 

 and of a fuller red; tilU at length, they refcmble an impalpable powder of the red 

 haematites. This fort may be obferved like an efflorefcence on the furface of the 

 haematites, found at Ulverftone, and other places on the borders of Lancafhire. And, 

 as gradations, fimilar to thofe between the eifenmann and eifenrahm, are to be obferved" 

 in the varieti.;s of haematites, I am inclined to embrace the opinion which Wallerius 

 feems to have forined, when he applies the name of haematites micaceus to the eifenmann 

 and eifenrahm : For I ftrongly believe, that a great part of the varieties of haematites have 

 been derived from the matter of thefe by a ftalaftitlcal operation with the advantitious 

 acceflion of fome argill and filex. 



" The oxydation of the eifenrahm is even carried fb far as to form tranfparent la- 

 mellar cryftals, about yV of an inch broad, exaftly like mica, of a beautiful deep garnet 

 colour. This variety, I believe, has only been found in Dauphine ; and the only fpe- 

 eimen in England I purchafed at M. de Calonne's fale. In refpe£l to your fon's fpeci- 

 men, it feems to be a variety of eifenrahm, in which fome of the charaflers of eifen- 

 mann are blended. A fimilar kind I have had from Luxillian in Cornwall; and when I 

 was at Exeter, I faw great quantities of the eifenmann for fale; but the place where 

 found was kept a fecret. Soon afterwards, however, I had occafion to vifit fome tia 

 mines on Dart Moor; and in one called Vytifor, I difcovered the eifenmann forming 

 thin veins between the main lode, or vein of tin ore, and the walls; and this was the 

 »inc from which Exeter had been fupplied." ^ 



