id s
duced to a fandy powder. Tills variety
may be termed fandy lead ora.
Cryftals appearing femi-metallic: fome-
times one part of the fame cryftal a dull
blue colour, the other tranfparent hora
Colour.
A lingular variety of carbonated lead
occurs in ferruginous earth, in nodules, with
Iiydrophanous fieatite, <&e. appearing like a
decompofed breccia, in fmail femi-tranfpa-
rent veins.
Thefe ores have hitherto attracted little
notice; nor indeed, till within thde
few years, Was it known that they contained
lead.
An argillaceous variety, called wheat
ft one, is found in a large vein. It is of a
light (tone colour, very heavy, with black
fpots, and contains arfenic. It is not tranf-
parent: fradure earthy, with a few bright
metallic
107
metallic Icales, and fometimes traces of
fmail femi-metallic veins. This variety is
extremely eafy of fufion, during which it
emits a ftrong fmell of fulphur and arfenic.
Phofphate of lead, of a leek green
colour, in hexagonal prifms, is fometimes
found on barytes, attached to fand-ftone.
Molybdate of lead, of a fine yellow
colour, approaching to orange, fometimes
appears in the cavities of galena, and of
carbonated lead. This variety I have fel-
dom met . with in this county,
Galena generally yields from 50 to 8o
per cent, at the furnace; many arts are
pradifed in the dreffing, to make it appear
clean and rich, in order to fetch a higher
price, which are well known to the fmelters
or ore buyers,
The carbonates of lead are fo full o f
heterogeneous matter, that they rarely
yield