Brush and Dana—Fairfield Cownty Minerals. 49 
It is evident from the above, independent of the micro- 
scopic examination, that the substance analyzed is nota simple 
mineral. If we assume the 8°84 per cent at phosphoric acid to 
be combined with sufficient lime to form the mineral apatite, 
and deduct this amount and also the insoluble matter, we have a 
remainder of 75°19 per cent, which when calculated to the orig- 
inal amount gives the following composition :— 
SiO, 27°43 M, 87 
A10, 9°42 CaO 0°95 
FeO, 3°54 Na,O 0°68: 
FeO 25°89 K,0 012 
MnO 2°9. H,0 11-70 
99°54 
It is scarcely admissible to attempt a formula for a substance 
which is so evidently a mixture, but we believe the results 
indicate that the green mineral is unquestionably a variety of 
chlorite. The analysis, excluding apatite and the insoluble resi- 
due, brings the composition very near that of delessite and pro- 
chlorite. Its physical characters, also, confirm its claim to be 
referred to the chlorite group. 
The mineral gives water in the closed tube, and B. B. fuses 
to a black magnetic mass; with the fluxes it reacts for silica, 
credit its being this species, although the pyrognostic charac- 
ters, rhombohedral form (RA R=96 
rtz. 
e chabazite has a vitreous to sub-resinous luster. The 
hardness is 45 and the specific gravity is 2°16. 
Am. Jour. ee Tne Serres, VoL, XVIII, No. 103.—Jury, 1879, 
