392 = New Minerals from Monroe, Orange Co. © 
Art. XXXVL—Two New Minerals from Monroe, Orange Co. ; 
‘ ~ by Cuarzves Upnam Sueparp, M.D. x 
st 1. Dimagnetite. 
~ Prmary form, right rhombic, prism, M:M=130°, (common 
niometer). Crystals in elongated prisms, with smooth, or but 
faint longitudinal strie. Color iron-black. Lustre of faces feeble. 
Cleavage parallel with M, and traces also with the shorter diago- 
nal. Fracture conchoidal to uneven, attended with imperfect 
metallic Instré. Opaque. 
=5°5...65. Gr.=5:789 (on a single trial of about 2 
grains weight). Magnetic with polarity. oe 
- Before blowpipe, conducts like magnetite, with which species, 
it is probably identical in composition. 
It oecurs implanted upon erystals of magnetite. The longest 
crystals observed measure about 14 inches. They sometimes 
ct a tendency to composition, after the manner of ‘stau- 
rotide. ne ‘ : 
The name is applied out of regard to the now supposed di- 
‘morphic character of Fe¥e. , 
. 2. Jenkinsite. _ 
~ Primary form, probably a rhombic prism. Occurs implanted 
upon massive maguetite and dark green pyroxene, forming vel- 
vety coatings, usually thin and even, but sometimes rising into 
irregular columnar (subfibrous) masses, one-third of an inch thick, 
somewhat resembling certain drusy varieties of arragonite. Its 
general appearance however is more strikingly that of the Cornish 
skorodite, which it resembles in its blackish green color, though 
it often has a shade also of olive, and when powdered, of pis 
tachio-green. Lustre vitreous, feeble. Translucent. 
¥ H.=2:6. G.=2:4...2:6. Before b owpipe emits moisture, 
immediately blackens; and becomes strongly magnetic. When 
the heat is strongly urged, it melts into a dull black globule at 
the end of thin fragments. With borax, gives a glass stained by 
iron. Easily soluble in aqua regia, with separation of silica. _ 
contains no alumina, (alkalies were not sought for); and consists 
of silica, peroxyd of iron, ia and water. 
As a species it will stand, both chemically and mineralogically, 
near to the picrosmine of Engelburg, Bohemia. : 
It is from the same locality with the dimagnetite; and 1s 
named after Mr. John Jenkins, of Monroe, to whose kindness I 
am indebted for the specimens of both, and to whom mineralo- 
gists owe many interesting substances which he has brought to 
light in his vicinity. 
Charleston, Feb. 23, 1852, 
