IRON. 
399 
faces of the crystal are somewhat curved as in pearl spar. Before the blowpipe it decrepi¬ 
tates, but at length becomes of a darker colour, and is slightly attracted by the magnet. It 
is soluble with effervescence in dilute muriatic acid. An analysis gave the following results : 
Carbonic acid,... 45.00 
Lime,... „ .... 28.00 
Magnesia,.... 13.75 
Protoxide of iron,_____ 11.25 
Moisture and loss,.... 2.00 
Except in the absence of a small proportion of manganese, the above composition is quite 
similar to that of the ankerite by Berthier above given.* 
Specimens resembling the above, are also found in the rock accompanying the iron ore at 
the Parish ore bed in St. Lawrence county. But the carbonate of lime and carbonate of iron 
are so liable to accidental mixtures, that the minerals having this composition require to be par¬ 
ticularly examined. 
In Massachusetts, ankerite is said to have been found in the coal formation at West-Spring- 
field. 
COPPERAS. 
Fer Sulfate. Hairy .— Sulphate of Iron. Cleaveland and Phillips. — Copperas. Shepard . •—Hemiprismatic Vitriol. 
Jameson. — Hemiprismatisches Vitriol-Salz. Mohs. — Melanterie. Beudant. 
Description. Colour various shades of green passing into white, but more 
frequently, owing to exposure, it is externally of a yellow or yellowish brown 
colour. Streak white. It occurs massive, pulverulent, and in stalactites. By 
solution it may be obtained in crystals, the primary form of which is an oblique 
rhombic prism. Fig. 474. M on M / 82° 2P; P on M 99° 23k Cleavage 
parallel to P perfect, less so parallel to M. Fracture conchoidal. Lustre 
vitreous. More or less translucent or transparent. Hardness 2.0. Specific 
gravity from 1.84 to 1.97. Before the blowpipe on charcoal, it becomes mag¬ 
netic, and colours glass of borax green. Its solution in water becomes black 
on being mixed with the tincture or infusion of galls ; and with chloride of barium, it gives an 
abundant white precipitate. 
Composition. Protoxide of iron 25.70, sulphuric acid 28,90, water 45.40 ( Berzelius). 
The formula of pure copperas is Fe0.S0 3 +7Aq. 
Geological Situation. It is almost always found associated with iron pyrites, from the 
decomposition of which it has its origin. It most frequently accompanies coal. 
After the statement that has been made in regard to the occurrence of this species as the 
result of the decomposition of iron pyrites, it will not be necessary to refer to particular 
Traite des Essais par la voie seche, I. 494. 
