SECT. III. 
Magnanefe. 
SECT. IV. 
Molybdsena, 
or the pencil 
lead. 
SECT. V. 
Cobalt. 
130 NATURAL HISTORY 
Manganefe, a ferrugineous mineral, ufed to attemper and bring 
glafs to its proper luftre d , has been lately difcovered near Tregofs 
moor, in the parifh of St. Columb ; the load is twenty feet wide, 
and fo near the furface that one ton may be raifed for one {hilling 
and fix-pence ; there is fome iron in it, and a great deal of the 
coarfe lapis h<z?natites : but there muft be fomething much more 
valuable than iron; for, in the year 17545 a ton of this ore was 
fent to Liverpool, and thence to Boflam, forty miles diflant, and 
was there fold for five pounds eight {hillings and fix-pence « : but 
though many tons have been raifed, the adventurers meet with very 
little demand for it ; one, among many proofs of the want of in- 
tercourfe and correfpondence betwixt Cornwall and the proper 
markets for minerals. Dr. Woodward, Cat. vol. I. page 30, men- 
tions a confiderable quantity of manganefe, difcovered about three 
miles from Penzance. 
In the year 1750, in a mine near the town of Penryn, were 
difcovered feveral bunches of load-ftone ; having tried and armed 
fome pieces of them, I found their magnetifm not ftrong, and the 
prefent perfection of artificial magnets renders the labour of fearch- 
ing further after natural ones entirely needlefs. 
I have one fpecimen only of molybdaena ; the ftone to which it 
adheres is very like the more gritty kind of lapis calaminaris, which 
fometimes contains lead : fome fmall gravels or this will mark paper 
as free as the molybdaena from Cumberland ; the gravels are about 
a third of an inch in bignefs. They came from a work in Camborn, 
called Huelcrafty, whereabouts very likely there may be more of this 
very fcarce fofiil to be found. 
In the year 1754 the fociety at London, for encouraging arts 
and ufeful difcoveries, thought proper to offer a premium of thirty 
pounds for the belt cobalt difcovered in England ; and a difcovery 
of this kind being made in the lands of Francis Beauchamp, Efq; 
in Gwenap, the mineral found was fent to London in December 
1754, and honoured accordingly with the premium; and as the 
different arfenicks, as well as zaffer and fmalt, (ot great ufe for 
ftaining glafs blue, and painting in oil-colours) are procured from 
Cobalt, and hitherto imported at a great price from foreign coun- 
tries, it is wifhed that this difcovery may be compleated, and, by 
keeping our money at home, be of ufe to the nation in general, as 
well as profit to Cornwall in particular. At prefent the Cornifh 
d Cramer’s Theor. page 201. foreft of Dean ufually at the price of twelve Ihil- 
e Iron is delivered at the iron-works from the lings and fix-pence per ton. 
