144 On Crystallized Native Terrestrial Iron, &e. 
In some of the crystals, the acute terminal edges, F’, were replac- 
ed by one or two planes ; but their dimensions were too small to ad- 
mit of ascertaining their inclinetions to the adjoining faces. 
These crystals cleaved with ease parallel to the planes P,'T, and 
M; thus, giving rise to the doubly oblique prism, as their primitive 
nucleus. on T is given above ; the remaining angles are, 
Ree ee et oe i ee 
M on T ee aoa a AS 
‘The utmost accuracy is not claimed for these measurements, which 
were made with the common goniometer, and must therefore be re- 
garded, only, as approximations to the truth. 
Externally the crystals were of a black color, and so soft as to be 
scratched with a knife; but, within, of a reddish brown color, and 
of the hardness of felspar. Specific gravity 3-4. Reduced to pow- 
der and treated with muriatic acid, they partly dissolved, the inso- 
luble remainder assuming a white color. Before the blowpipe, like 
_ the massive portions with which they were associated, they fused into 
a shining black globule attractable by the magnet ; and with borax 
they gave a violet glass. 
The common lamellar variety is disseminated through quartz in 
plates, quite after the manner of Clevelandite Felspar. When amass 
of the rock containing it, is freshly broken, the ferro-silicate of man- 
ganese presents a pale rose-red color with felspathic lustre, and might 
be mistaken for that substance ; but whenever the air has found ac- 
cess to it, its color and lustre are changed, as well as hardness, and 
even chemical constitution, as is supposed by Dr. Thomson. 
3. Anthophyllite in Haddam, ( Con.) 
This mineral is found upon the east side of the Connecticut, in 
an extensive quarry of flagstone. It exists in connexion with a fibrous 
brown tourmaline, (which is sometimes in distinct crystals,) and a 
granular decomposing iron pyrites ; forming very often, a third part 
_of the mass in bulk ; and may be obtained in any quantity desired. 
The tendency of the pyrites to decompose, frequently obscures the 
characters of the anthophyllite ; but, when a mass is freshly broken, 
it presents the mineral so much resembling the Norway specimens, of 
the same substance, in the color, lustre and mode of aggregation of 
its crystalline fibres, that it is impossible to distinguish them apart.— 
The crystals are occasionally, remarkable for their distinctness avd 
