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Tin . 
It appeared like a thick jagged or scolloped laee or edg- 
ing, and was found at St. Austel in Cornwall, England. 
2. In the form of crystalline metallic laminae, or flat crys- 
tals, rising side by side out of an edging, which shone 
like melted tin. They were nearly as thin as the leaves 
of talc, intersecting each other in various directions, with 
some cavities between them, within which appeared many 
specks and granules of tin that could easily be cut with 
a knife ; this also came from Cornwall 3. In a massy 
form, more than an inch thick in some places, and enclos- 
ed in a stone resembling quartz, which was taken to be a 
hard crust of crystallized arsenic. 
All the ores of tin hitherto found, except the sulphuret 
from Huel or Wheal Rock, St. Agnes, Cornwall, are in 
the oxided state. They are remarkable for their great 
weight, which is between 5.8 and 6.97, according to 
Klaproth. 
The common ore, called tin- stone, has a vitrified ap- 
pearance, resembling a garnet of a blackish- brown colour, 
but much heavier. Its surface is shining, sometimes 
striated, and its fracture lamellar ; soft enough to be cut 
or scraped with a knife, and affording a pale red powder. 
Some authors assert, that it contains arsenic, but Kirwan 
positively denies the existence of arsenic as a mineralizer 
of tin. The Germans call the irregular compact tin ore 
by the name of zinnstein ; but the crystallized tin-stones 
are called zinngraupen, if the crystals be distinct and 
somewhat large. The zinnzwitter ores, in which the 
crystals are small, and not so distinct, resemble small 
grains, scattered through a compact raw tin-stone, or a 
stone of any other kind. 
The common matrix of tin in the Cornish mines is the 
killas, and the growan. This consists of white clay, mix- 
ed with mica and quartz, without any particular texture ; 
which, when lamellar and hard, is called gneiss by the 
