OF CORNWALL. 131 
are entirely to feek for the method of allaying, and even diftin- 
guiflhng critically the cobalt from its various mixtures in the mine ; 
and till the cobalt is carefully felected, it will probably be of little 
value. In the fame load there is a good deal of Bifmuth, not only 
where the cobalt is, but fo prevailing in other parts of the mine, 
that it may as juftly be called a mine of bifmuth as of cobalt*; and 
bifmuth being of great ufe for hardening and perfecting pewter, 
&*c. and many thoufand pounds fent out of the kingdom yearly for 
it, this mine will, it is hoped, prove as valuable for its bifmuth as 
its cobalt, under proper direction. 
Native rock-falt, or fait from fprings, or pit-coal, I have never 
yet heard of found in Cornwall : thefe feem to be the portion of 
other parts of England ; fome countries are favoured with one thing 
under the foil, fome with another, and Cornwall has little reafon to 
complain of her allotment. 
Dr. Woodward® mentions a fulphur-ore from Redruth, and native 
fulphur in a mafs of antimony from a mine in St. Kew parifh \ This 
is the yellow matter that covers and interlaces the veins of antimony 
in the parifh of Endelian : at the mine it is unCtuous, and bums 
freely with a blue flame 
But of all our foflils, which are mineral only, (as far as is yet sect. vi; 
difcovered) and not metallic, that which we call Mundic offers itfelf 0f Mundic > 
in greatefl: plenty, every where almofl: intermixed with tin, lead, 
and copper, but fometimes found making a lode or vein by itfelf 
without any metal near it. 
This is fometimes called a Pyrites, but better known among Na- 
turalifts by the name of Marcaflte k , a name proper enough for any 
foflil, which, for ought we know at prefent, has only the appear- 
ance, mark, or outward teftimonies of metal, fuch as weight and 
colour, but oftentimes ufed as well to exprefs a foflil any-ways re- 
markable for the regular figuration of parts, or glitter of its furface. 
The Cornifh name is Mundic, from the cleanly Alining appearance 
both of its furface and ftructurc, and to this name I fliall confine 
myfelf. 
This femi metal is varioufly coloured on the outfide with blue, sect.vii. 
green, purple, gold, filver, brafs, and copper-colours ; but, exa- Colour, and 
mining it at the fraClure, I find only three diftinCb colourings, which 
f The bifmuth was quite thrown away till the s Vol. II. Cat. page 17. 
learned and fagacious Dr. J. Albert Schloffer, h lb. page 20, g, 3. 
F. R. S. came to view it September 8, 1755, who 1 lb. g, 12. 
extracted the cobalt tint for glafs and fmalt, and k Italice Marcafita a verbo marcare, to flamp 
at the fame time feparated and prefer ved the or mark any thing. 
Bifmuth. 
I diftinguifh 
