OBSERVATIONS. 
27 
Whitifh grey copper ore, cryftallized 
in fmall triangular and quadrangular 
pyramids, whofe points are generally 
truncated, is found along with folid 
grey copper ore at Poldice and Dol- 
coth. But the richeft copper ores are 
the folid grey from Trefeavean, Retal- 
lack, Cook-kitchen, Carrarach, Huel 
Virgin, Redruth. Some of thefe may 
be cut with a knife like foft vitreous 
lilver ore, particularly thofe from Tre¬ 
feavean ; the analyfis of thefe lafl is 
given under No. 3. 
Yellow copper ores are found at Pol¬ 
dice, Hallamanning, Dol-coth. From 
the latter mine, which is it>o yards 
deep, and yet elevated 60 yards above 
the level of the fea, the mod remark¬ 
able is a ftaladtitical ore, of an hemif- 
pherical form (Run-yellow copper) which 
is often variegated with the colours of 
blue fteel or red copper. Calciform 
copper ores of great variety are likewife 
found in Cornwall. The rare crydal- 
lized 
