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fracture. Another variety, when broken, is
remarkably bright and foliated ; by expofure
it becomes tarnifhed and decompofes.
Another kind of galena is called the fteei
grained lead ore; being very hard, and the
granulated appearance,, when broken, refem-
bling the fracture of fteei• This ore fome-
times appears fibrous, not unlike the common
compact ore of antimony.
]Vi afles of galena frequently contain fmali
holes, the furfaces of which, being nearly
black, appear as if corroded. Sometimes carbonate
of lead appears on it, in various ftates
arid forms ; fame of the cryftals having a
femi-metallic appearance, others of a dirty
white, and fome tianfparent: the lhape is
chiefly the prifm, and the double hexagonal
pyramids joined at the bafe.
Two, three, or four veins of galena
fometimes occur in barytes, the whole not
broader than two and a half inches, Thefe
veins
veins are perpendicular, and afford a pleating
image of the large veins of ore.
Spherical nodules of lead. ore are not
uofreqoently found in caverns in the
mines, whither they muft have been eon*
veyed by Water. Some of them are hollow,
and contain native fulphur.
A pulverulent black lead ore, fometimes
diflerriiriated on the matrix, appears to arife
from the decompofition of the galena, owing
probably to their fupfcr oxygenation.
Slickenfide is a Angular variety of galena,
appearing of a bright metallic luftre, with
a reflection approaching to that of a mirror.
It is thin, as if it only plated on one fide of
a fubftance called kcvel; and forms the fide
of a vein or of a cavity. When firft pierced
it cracks and flies with violence, as already
mentioned. A new variety of ftitkenfide of
a metallic luftre, coated Writh blende of a
light ftone colour, fometimes dark hrowri
b 4 on