C 38 ] 
and in fome places more than one inch thick ; but 
unfortunately the perfon employed to difcover the 
contents, injudicioufly broke the outward cruft all 
to pieces, by which means he got all the pure metal 
indeed, but prevented that abfolute convidtion, which 
this noble fpecimen would otherwife have conveyed 
to the doubtful. However, the like ftrudfure of the 
cruft, and that of the before-mentioned fpecimens, 
and its connexion, to fome fragments ftill in the 
keeping of Mr. Rofewarne, with the granulated 
furface, and fhotten edge, of the metal, pronounce 
it, upon comparifon, to be native tin. 
The cruft, incloling this third fpecimen, was 
certain done of the quartz kind, very hard to 
break, and exadtly the fame, to all appearance, 
with that of the firft mafs. I employed a tinner 
dextrous in vanning (a way of breaking and trying 
ores, by wafhing them on a fhovel gently with wa- 
ter) to try it in his ufual way ; he bruil'ed it in my 
fight, and obferved to his furprife, that it differed no 
diminution, or decreafe, as all other ores do 5 that 
it was very rich in its kind ; that he had never feen 
any fuch before ; and that he could not fay what 
metal it contained. 
Thus far is the relation Mr. Borlafe gives ; but as 
the exiftence of native tin is fo univerl'ally doubted, 
I thought it neceffary, that other proofs than a meer 
hiftorical account, and the exhibition of only two 
fpecimens, and both from the fame hand, fhould be 
produced to prove it. Mineraliffs might then doubt 
whether what Mr. Borlafe calls tin, was really that 
metal, or rather an arfenical marcafite, or other mi- 
2 neral, 
