J^ Al^ALYSIS OF A MINERAL, &C. 



III. 



Analyfis of a Triple Sulphuret of Lead, Antimoni/, and Copper, 

 from CormualL Bij Ch/^rles Hatchet, Ef({. F. R. S. 

 From the Philofophical Tranfadiom for ISO^. 



Hiftory of the JL HE fiibftance which forms the fubjed of this paper, has 



"""" • hitherto been regarded as an ore of antimony ; it is extremely 



rare, and has only been obtained from Huel Boys, in the parifti 



of Endellion, a mine which, from deficiency of profit, has for 



fome time been abandoned. 



The fcarcity of the ore has probably been the caufe of its 

 being unknown to foreign mineralogifts ; indeed few even of 

 the Britifii cabinets poflefs it; but theraoft perfect and beautiful 

 fpecimens are (as far as I know) to be feen in the fplendid 

 colledion of Philip Rafhleigh, Efq. of Menabilly, in Corn- 

 wall. 



To Mr. Ralhleigh we are indebted for the firft defcriptlon 

 of this ore* ; but no fubfequent notice had been taken of it, 

 until the preceding paper was written by the Count deBournon, 

 whofe eminent merits, as a mineralogifl: and cryllallographer, 

 are well known to this Society. 



I. ^ 



Sp. gravity. The fpecific gravity of this fubftance is 5766, 65' of 



Fahrenheit. 



II. 

 Heat by the If fuddenly heated on charcoal, by the blowpipe, it crackles 



blow-pipe ex- gj^j {^\\i^ j but, when gradually expofed to the flame, it 

 5Sdwhu!ffumes, liquifies, and, upon cooling, aflumes a dull metallic grejr 

 and left fulphu- colour. 

 »et^i!'copper. When the globule was longer expofed to heat, white fumes 



(which at firft had a fulphureous odour) were evolved, and 



partly fettled on the charcoal. 



Ebullition prevailed during the difcharge of thefe white 



fumes ; and the globule gradually fuffered conliderable dimi- 



nution, remaining at length tranquil, and of a very dark gray 



colour. 



* Specimens of Britlfti Minerals, felefted from the Cabinet of 

 Philip Rafhleigh, Efq. F. R. S. &c. Part I. page 34, Plate XIX. 



Upon 



