354 
! Tim . 
at 45° of Fahrenheit, is 5.80, and even 6.45, It contains 
some arsenic and a considerable portion of iron ; and 
gives sometimes 6J.5 per cent, of tin. It is very scarce, 
and found only in small pieces. 
The tin spar, or white tin ore, is generally of a whitish 
or gray colour ; sometimes it is yellowish, semitranspa- 
rent, and crystallized, either of a pyramidal form, or irre- 
gular. It resembles a calcareous, or rather ponderous 
spar, but is easily known by its great weight, and shining 
greasy appearance, its fracture also is vitreous. It was 
formerly thought to contain arsenic, but Margraaf found 
it to be the purest of tin ores ; though it is said to contain 
sometimes a mixture of calcareous earth. Its specific 
gravity is=6. 07. 
The grains are of a spherical polygonal figure, like the 
garnets ; but seem more unctuous on their surface. It is 
found either in large or small grains. 
Bergman received a specimen of native aurum musivum 
from Nerschinskoi in Siberia. It resembled the artificial 
aurum musivum externally, or rather the aurum musivum 
formed a crust environing a nucleus radiated in its frac- 
ture, and resembling a white metal. It yielded to the 
knife, and the place of section exhibited a variable colour* 
Its powder was black. By the analysis, it proved to con- 
sist of tin mineralized by sulphur, with a very small por- 
tion of copper. In the Journal de Physique for 1 783, it 
is said, that the specimen was too small to admit of a de- 
termination of the quantities in the large way : but in the 
preface to the Sciagraphia it is said, that the native aurum 
musivum contained forty parts of sulphur to one of tin % 
and the other mineral, which resembled antimony, contain- 
ed one fifth part of sulphur only. 
At Huel Rock, in St. Agnes, in Cornwall, there has 
been found a metallic vein nine feet wide, at twenty yards 
beneath the surface. Raspe was the first who discover- 
