OF CORNWALL. 197 
with great fecurity, that there is no richer copper, nor a greater 
variety of ores any where than in Cornwall. 
Copper is found fometimes depofited on the fides of fiflures in sect. 1. 
thin films, which are no more than the fediment of waters ifluing fojjj atftate 
from fome copper lode ; fometimes in fpots and bunches irregularly 
difperfed, but rnoftly in fiflures, in like manner as the tin-lodes. 
Copper lodes throw from them few fhodes, fo that they are not 
often accefiary to their own difcovery ; the reafon of which is, that 
there is feldom any copper on the back of the lode, fo as to constitute 
a broil\ but when there is, and that copper is heavy, and promotes its 
own removal downwards by its gravity, copper lodes throw fhodes as 
well as thofe of tin, of which feveral inftances might be produced. 
Veins of copper are oftentimes by the fedulous difcovered in cliffs, 
where they are laid bare by the fea, copper being much eafier dis- 
cerned than tin. The mod; encouraging leader to copper is what 
the Cornifh call Goffan, which is an earthy, ochrous ftone, ruddy 
and crumbling, like the ruft of iron. Where the ground is incli- 
nable to an eafy, free, blue killas, intermixed with white clay, the 
miners think it a promifing fymptom. A white cryftalline ftone is 
alfb reckoned very retentive of yellow copper. The ore does not 
lye at any one certain depth ; but it is a general rule, that when 
copper is found in any lode, that lode fhould be funk upon, it 
generally proving better at fome depth, than when it is firft 
touched. 
That ore which is moft common is of a yellow brafs-colour : it sect.il 
is found adhering to ftones of all kinds, but pureft commonly in 
the white opake cryftal, or in the white clay, and according to the lours and 
quantity of the barren ftone intermixed, fells from five to fifteen texU,rc ' 
pounds per ton. Of this yellow ore there are different forts : fome 
not only looks like mundic in texture, but is fhaped into cubes (as 
the yellow mundic generally is) and will bear aqua forth without 
Stirring, and yet has been found to be real copper-ore, and worth 
eighteen pounds per ton ; but the beft fort of yellow is the flake- 
ore, called fo from the clofenefs of its texture, which is as fmooth 
and glofly as brafs, and not more porous : this fort is not fo brittle 
as the former yellow, and has undergone the purification of a men- 
flruum , being probably no more than the firft-mentioned common 
yellow diffolved and depofited in the mine : it is found commonly 
in thin, vifibly diftind, ftratous maffes, with its under parts of 
a bliftered buttony furface, (Plate xxi. Fig. in.) according as the 
drops of the folution fell from different parts of the roof (Plate ib. 
Fig. 11.). Where the folution is vifcous and lefs diluted, it forms tubular 
E e e (heaths 
