On Crystallized Native Terrestrial Iron, &c. 143 
Detoxide of Manganese, - - - - 17.716 
Peroxide of Iron, - - - - - - 6.480 
The residue, which became white, was composed of 
Silica, ~~~ - - - - - - 29.480 
Protoxide of Manganese, - - - - - 34.640 
Peroxide of Iron, - - - - - 6.740 
Moisture - - - - - ~ - 3.170 
98.226 
Dr, Thomson supposes the mineral to have undergone a species of decomposition 
externally, from the action of the air; the protoxide of manganese having been con- 
verted into deutoxide ; and originally, that the mineral must have been a compound 
ef four atoms silicate of manganese, and one atom persilicate of iron. 
The specimens examined were obtained through Dr. Torrey, from Franklin, New 
Jersey ; where this mineral has long been known to exist under the denomination 
of the Crystallized siliceous oxide of Manganese. 
The Ferro-silicate of Manganese, I found in Cumberland some 
years ago, at the same time I discovered the Yenite.* Both of 
these minerals occur, engaged in the same gangue, and were for a 
long time considered by myself, as identical, in consequence of an 
early blow-pipe experiment which I made upon them,—both fusing 
with equal ease into a black, shining globule, attractable by the mag- 
net; though the former I had not then met with, except in massive 
specimens. Afterwards, observing that it invariably appeared distinct 
from the Yenite, though accompanying it upon the same specimen, 
that it possessed a distinct threefold cleavage, and, moreover, a hard- 
ness above that of Yenite, I ceased to consider it any longer as such, 
and placed it among my specimens of doubtful minerals. Bee, 
Lately, however, my attention has been called to it by a specimen 
of the same substance, ticketed “ Yenite,” in a case of minerals pre- 
sented to the American Geological Society, by the late Dr. Robin- 
son. It was distinctly crystallized, and under a form quite incom- 
patible with Yenite. ‘The crystals consisted of parallel rows of short, 
thin, oblique angled prisms, traversing the mass, and leaving chan- 
nels between them. The largest of these did not exceed one fourth 
of an inch in length, one fifth in height, and one tenth in breadth. 
Their form is exhibited in the following diagram. . 
eS ee 
Pan? 2S cee 2 Bcd 
mM! k 
wa eo FO kK eat 
- on P oo OR i a : 
* Vide this Journal, Vol. VIE, p. 254. 
