Atcotfiit of, the Ores of Tellurium, J^jy 



Its matrix is compofed of quartz and marl. The fubjecl'of the firft analyfis was taken, 

 from a piece of the compadt variety detached in 1780. 



The graphic gold of the mine Francifcus at OfFeubanya, forming the fecond variety, is 

 of the white colour of tin, partly inclining to the yellow of brafs : it is very brilliant, 

 compofed of prifmatic crydals, flat and comprefled, of which the mutual pofition affedts 

 the form of the characters of Turkilh writing, which has given rife to its empyrical name. 

 It is ufually found between the greyifh blue argillaceous porphyry, bedded in grey 

 quartz. The proportion of the conftituent parts of tliis ore vary much : the middle term 

 lias been taken. 



The third variety, called the yellow ore of gold, is of a white filver colour Inclining 

 to the yellow of brafs, compaft, and interfperfed with quartz and brown fpar. It is 

 cot known whether that fpecimen which prefents radiations of confirierable magnitude, 

 and exhibits a lamellated texture and fra£lure, is of the fame fpecies : it is fouiid in a 

 mixture of quartz cryftals, and brown red fpar, and fometimes in the foliated ore. 



The foliated ore, or grey foliated gold ore of Nagyag, differs, in its chemical and mine- 

 ralogical charafters, from the three foregoing, which are comprifed under the name of 

 white gold ores ; which has caufed it to be admitted, in the new fyflem of mineralogy, 

 as a particular fpecies of the genus Gold. Its colour is a deep leaden grey, inclining to 

 the iron black. It is feldom found compadt, but mofl: commonly inferted in the form of 

 fmall united leaves, and likewife in thin, oblong, hexahedral tables, partly accumulated 

 in cavities. Its metallic fplendor is but moderate : its fra£lare moft commonly exhibits 

 contorted leaves ; it is fpeckled, and in fome fpecimens the leaves are flightly flexible. Its 

 matrix is compofed of quartz mixed with reddifli manganefe, which it has penetrated in 

 «vcry dirc£lion. 



Scopoli, Sage, and Ruprecht, attempted to analyfe this ore ; but the difference of their 

 tefults rendered their experiments very uncertain. They had clearly afcertained the pre- 

 fence of a fubflance volatile by heat ; but they were deceived in taking it fometimes for 

 trfenic, and in other inftances for antimony. 



It is to M. Von Muller, at prefent diredor of the mines at Zalathna, that M. Klap- 

 roth afcribes the honour of having firfl obferved this new metal (in the colledion of Me- 

 moirs of the United Friends of Vienna, publiflied by Born). He cxprefles his acknow- 

 ledgment for the fpecimens he fent to him, which enabled him to prove its cxiftence. He 

 does not omit the obfervation, that Bergman, though he durft not decide concerning the 

 true charadter of this metallic fubftance, did neverthelefs declare that it was not antimony. 



We have feen. In the foregoing abflrad, (p. 372, No. 3.) that the precipitate' which is 

 not re-difTolved by ammoniac is a mixture of gold and iron. There are, doubtlefs, feveral 

 methods of feparating thefe two metals \ but, perhaps, it may be fatisfadlory to know the 

 method which was ufed by M. Klaproth. He re-diffolvcd the whole in the nitro-muriatic 

 acid, and precipitated the gold by a folution of the nitrate of mercury made without heat, 

 which he poured gradually into the former folution, till the precipitate which fell down 

 had changed Its brown colour for white. The precipitate, being carefully colleifled, was 

 reduced Into pure gold. 



" I {hall give," fays M. Klaproth^ " In tlic third volume of m^ Beytraege, &c. the 



particulars of thcfc analyfes of the gold ores of Tranfylvania which contain tellurium, 



■ • ih-xk J C a- after 



