- 
264 ANALYSIS of a4 COPPER ORE 
Eee 
Analysis of the Grey Coprrer Ore, from Airthrey. 
THE copper mine of Airthrey, near Stirling, confifts 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 requeft of 
one of the proprietors... The fpecimens which were employed 
for the fubfequent analyfis, were the pureft that I could feled, - 
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 {melted. 
Tue 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. 
Tue colour is at firft light fteel-grey ; but the furface foon 
tarnifhes, and becomes of a dark dull leaden-grey, and in fome 
places aflumes a beautiful tempered fteel tarnifh. ,Maflive and 
difleminated. In fome {pecimens, it exhibits the appearance of 
imperfect cryftals. Internal furface fhining and metallic ; but, 
by expofure, it foon becomes dull. Fracture fmall-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 feratch 
each 
