U. U. Shepard—Mineralogical Notices. 403 
Analyses. 
Mean 
P.O. 40°39 39°44 39°75 39°86 
CaO 50°04 50°89 49°51 50°15 
sO 2°57 1°75 2°16 
HO 7°56 7°56 
Deducting 99°73 
2°16 SO,=1°5¥ CaO=0°97 H,O=gypsite, 
95°09 
Raised Molecular Approximate 
Remaining. to 100. weights. _ ratios. 
P20) 39°86 41°92 + 142 = 0°295 I 
CaO 48°64 5115 > 56 = 0°913 3 
H,O 6°59 6°93 + 18 = 0-385 14 
95°09 100-00 
Or corresponding to Ca,P,0,+H,O with some slight excess of 
moisture, probably hygrometrie. 
wo minerals, monite and monetite, are much inter- 
ees constituting together three-quarters of the variously 
zed masses, whose remaining quarter consists of gypsite and 
calcite, the latter however in isolated patches and in much the 
least proportion. The remarkable feature of the egate as 
comin stone-guano formation, consists in the ent 
absence (in masses, half a foot in thickness), of all traces of 
organic The monetite is the most abundant species, 
broad; and inasmuch as its crystals are confusedly aggregated 
and rather sharp, the specimens are exceedingly ro ugh to the 
with the latter, the aggregate is often arranged in imperfect 
layers, separated by intervals of about one-sixth of an inch 
filled by the mons A cross-fracture of such masses displays 
an obscurely banded appearance. Rarely the monetite presents 
globular concretions, with a sub-fibrous structure. It is also 
sometimes granular, but then pure it is rarely impalpable. 
The asso cated aypsit is white, in small shining crystals, in 
coarse Abroas sudividualy small globules, fine granular and 
pulverulent. The calcite is in distinct, semi-transparent crys- 
tals, having the form of acute rhomboids, analogous to those 
resulting from the slow evaporation of brine-waters. The pres 
ence of silica, or some insoluble silicate is detected in the analy: 
ses of the aggregate only, where it varies from 0° ~ 2° per cent. 
Am. Jour. a —Tuirp ee Voi, XXUIT, No, 187.—May, 1 
