264 ANALTSIS of a COPPER ORE 



Analysis of the Grey Copper Owe, from Airthrey, 



The copper mine of Airthrey, near Stirling, confifls of a 

 thin vein, which runs through the weft corner of the Ochils. 

 It has been twice wrought, by two different companies. But, 

 in both cafes, was abandoned, after a few years trial. I went 

 to it fome years ago, and examined the ore, at the requefl of 

 one of the proprietors. The fpecimens which were employed 

 for the fubfequent analyfis, were the purefl that I could felect, 

 out of a confiderable quantity. I was told, however, that from 

 the lower level, which was at that time full of water, much 

 richer ore had been extracted. But, afterwards, when the lower 

 level was freed from its water, I went down to it myfelf, and 

 found the ore precifely of the fame kind as in the upper, with 

 this difference, that it was more mixed with calcareous fpar, 

 and perhaps, on that account, more eafily fmelted. 



The veinftones in the Airthrey mine are fulphate of barytes, 

 and carbonate of lime, and with thefe the ore is almoft always 

 more or lefs mixed. 



The colour is at tirft light fteel-grey ; but the furface foon 

 tannines, and becomes of a dark dull leaden-grey, and in fome 

 places afiiimes a beautiful tempered fteel tarnifh. Maffive and 

 diJTeminated. In fome fpecimens, it exhibits the appearance of 

 imperfecl: cryftals. Internal furface mining and metallic ? but, 

 by expofure, it foon becomes dull. Fracture final 1-grained, 

 inclining to even. Fragments indeterminate, and rather blunt- 

 edged. Semihard, the degree being almoft the fame as that of 

 calcareous fpar ; for thefe two minerals reciprocally fcratch 



each 



