402 Crystal of Phosphorite from Hurdstown, N. J. 
ating and becoming ash grey ; at a higher temperature melts into 
an apple-green blebby glass. The pebbles are porphyritic with _ 
crystals of glassy feldspar, and contain occasional amygdules of 
carbonate of lime, surrounded with a jaspery red crust, and a thin 
layer of chlorite 
. Chemical analysis of the Pitchstone——The black mineral, 
ave picked, was reduced to fine powder by levigation—dried 
t 212° F., and analyzed in ote eoperete parcels of one gramme 
iit one for the silica, alum e, manganese, oxyd of 
iron, and water, and the other fans ue ‘akalis with the following 
results, per cent. 
See: : F s ‘ : : 67°90 
Alum ‘ : ; s; aed 
Batherd ‘of i iron, . ; ‘ ; 6:40 
Lime, : ; ee 
Oxyd of manganese, ° . , 0:80 
Soda, . ‘ ° + a 
Water, ; , ; ; ‘ 8:00 
100-01 
These results were verified by repetition on separate portions 
of the mineral, the water ‘having been distilled ina glass tube 
and proved to be pure, no organic matter of any kind existing in 
the mineral, and no alkali but 
It is evident that this mineral is analogous to the pitchstone 
porphyry of the island of Arran, in Scotland; and since it has 
not, so far as I know, been before discovered in the United States, 
these results may prove interesting to mineralogists. It is not 
known, whether it occurs in place in the trap ‘rocks, or in the 
questions, interesting to men of science. 
2. Crystal of Phosphorite from Hurdstown, N. J. 
- This crystal had a yellow color, and was remarkably resplen- 
Pa on the surface like those from St. Lawrence connty, Ne 
York, appearing as if fire-glazed. Its sp. gr. is=3-205. 
~ Chemical analysis.—By qualitative analysis, it was first proved — 
_ to contain fluorine and chlorine, phosphoric acid, lime, oxyd o 
iron, and manganese 
he fluorine is sufficiently abundant in it to cause ga etche. 
ing on glass, when it is disengaged by the action of sul en 
Specimens of this etchgng I exhibited at the meetings ' 
e American vies of aes and Sciences last t Ana ae 
