OF CORNWALL. 91 
the furface of the land in moft parts of Corwall, yields in great 
plenty, I mean an opaque whitifti debafed cryftal, commonly (but 
indeed erroneoully) called white fpar ; thefe ftones are extremely 
hard, and repair roads, and face our hedges ; being full of angles 
they make the beft pitch-work for paving courts, ftables, and the like; 
the pavement not eafily growing llippery, or breaking, where thefe 
ftones are well laid u . This ftone by the Germans is called Quartz, 
and becaufe we want a name for it in Englifh, it will be fo called for 
the future. It is vitrefcent, ftrikes fire with fteel, not foluble with 
aqua forth w , and is the general bafs of moft of our Cornifh ftones. 
In moft of our compound ftones in Cornwall, there is more or sect.ii. 
lefs of a black ftony matter which we call Cockle. Sometimes it is Cockle - 
intermixed as fpots and veins, and fometimes it is the bafs. Broken 
tranfverfely it is of a dull earthy black, fcarce fo bright as the duft 
of pitcoal ; it’s texture confifts of fibres parallel, and glofiy, thefe 
fibres make either lamina, frice, or granules x . It fhews itfelf every 
where fibrous, and when it is in its pureft ftate, and has neither 
metal, nor ftone different from itfelf (as we often find it in the pa- 
rifh of St. Juft) it fhoots into granules of irregular planes, inclinable 
to a prifmatick figure, not in the leaft flexible, but fhining and re- 
fembling in fhape, the granulated cryftals of tin-ore, and when free of 
earthy impurities, ponderous and fo near to the fpecific weight of that 
metal, that nothing but tryal by water or fire can diftinguifh the 
cockle from tin. It is nothing worth of itfelf, but ’tis either the 
bafs , or makes a confiderable part of our moft ufeful, and remark- 
able ftones. It weighs to water as 3— J is to 1 7 . 
Another common ftone with us in Cornwall is the Elvan 2 , ofsECTin, 
very clofe grit ; and fo extremely hard that it will not cleave, nor EW 
break to face or joint, and if tin-ore happens to be included in this 
ftone (of which there are feveral inftances in Senan parifh and elfe- 
where) ’tis not worth the pains of getting at, unlefs it be in greater 
quantities than what we generally find in fuch hard ftones ; if ufed 
in building it generally goes into the wall in the fame fhape that 
“ Two parcels in calks have been lately fent 
from Truro to London at the defire of fome perfons 
principally concerned in the porcelain manufacture, 
for which their colour and hardnefs feem to render 
them a necelfary ingredient, as well as for making 
of glafs, and fufing of copper. Linnaeus, Syftem. 
Nat. page 15 3. 
w Of the fecond genus of Linnaeus, Syft. Nat. 
page 153, it is the fecond fpecies. 
x Of both the former 1 have fome inftances 
from Caftle Treryn in St. Levin. 
r Dr. Woodward, Cat. Vol. ii. page 23, calls 
it cc a black thready mineral, feeming to be a 
“ fibrous talc.” Hill, page 499, calls it “ a fo- 
“ liaceous, black, cryftalline talc.” Linnaeus 
feems to have the fame body in his view among his 
mica:, in the fourth fpecies of his apyrites, genus 
7, page 1 59- See alfo his fecond fpecies of talc, 
pag. fequ. 
z Quafi ab Hel-vaen, i. e. the ftone generally 
found in brooks; unlefs it be a corruption of An- 
von, which in Cornifh fignifies a fmith’s anvil, 
and might fitly reprefent this very hard ftone. 
nature 
