Hematites, or liver ftone, is fometimes
found incumbent on a Solid mafs or ball;
pyrites, about a quarter of an inch in
thicknefs, the interior brafs yellow, diverg-,
ing from a centre.
The argillaceous iron ore is in the mOft
general ufe in the iron works. It forms
a thin ftratum in the coal countries, fometimes
enclofing (hells and coralloids. It
frequently occurs in nodules above coal,
containing vegetable impreffions. It is fometimes
mixed with a proportion of Lancashire
ore; which by ufing a proper quantity
of limeftone as a flux,, is found to be a
confiderable improvement.
Calcareous or fparry iron ores, are of a
fine brownifh red colour, fometimes bright
yellow,, fcaley,, ahd dirty brown, found in
amorphus maffes near the Surface, and filling
infulated places. The calcareous matter
Seems
feeftis prédominant, the cryftallization is frequently
preferved, and it appears in differ-*
ent ftages of decompofltion ; it is very ufeful
to mix with other iron ores, and is faid to
make a good iron for eonverting into fteel.
ManganeSe appears in the fhape of black
wad ; formerly fuppofed to be an iron ore,
in earthy maffes, crumbling to powder on
expofure to the atmofphere, being very loofe
and friable. Thefe black lumps are not
unlike hard balls of foot, but when broken,
capillary veins appear fomewhat of a metallic
luftre.
Black Wad muff not be confounded
with blackjack, which is a blende or ful-
phuret of zinc, or pfeudo galena, found in
amorphous maffes, frequently cryftallized,
and generally accompanying fluor and barites.
' The colour is a blackifh brown, inclining
to a metallic luftre, and a little
transparent.
H A variety,