C. U. Shepard on New Mineral Species. 



97 



having been subjected to the agency of heated trap rock, whereby 

 the greater portion of it has been thoroughly fused. The altered 

 guano is composed almost exclusively of two mineral species, 

 which I have called pyroclasite and glaubapatite, each of which 

 is essentially a hydrated phosphate of lime. 



3. Pyroclasite. 



Massive ; in large tuberose and reniform masses, much resem- 

 ' bling the menilite opal, from Menil Montant near Paris, except, that 

 they are flatter, more irregular, and rarely oval on both sides. In 

 this respect, they more resemble the large druses of calcedony 

 from Faroe, or the electric calamine from Cumberland. Structure 

 indistinctly concentric ; and when broken across (through masses 

 an inch thick) it presents a banded surface like agates or ribbon- 

 % jasper. Color, cream color : but on the botryoidal surfaces which 

 have been exposed to the weather, milk-white, and presenting 

 when viewed with a single lens, a very remarkable corroded 

 appearance, much resembling the vermiculated surface of marble, 

 as employed in architecture. Lustre dull, feebly resinous on a 

 fresh fracture. Opaque. Brittle. Fracture even, to sub-con- 

 choidal. H. =4-0. G. =2*36 . . . 24. 



Heated in a glass tube, it flies to pieces with a brisk decrepita- 

 tion, much of the mineral being at the same time projected from 

 the tube. At the same time, it turns of a dark color, emits mois- 

 ture and a feeble animal odor, not more perceptible however than 

 in many secondary limestones when heated. It is impossible to 

 hold a piece of the unheated mineral before the flame of the 

 blowpipe long enough to bring it to redness ; but occasionally, a 

 fragment large enough for this purpose, is left in the glass tube, 

 which will bear ignition in the platina forceps without flying to 

 pieces. It then instantly becomes white, phosphoresces strongly, 

 tinging the flame yellow, slightly tipped with green. At length it 

 fuses on the edges into a white glassy enamel : and the fragment 

 being placed upon a piece of moistened turmeric paper, occasions 

 a feebly alkaline reaction. The heated mass on being moistened 

 with sulphuric acid tinges the flame of the blowpipe momentarily, 

 of a still deeper green. The powdered mineral mixed into a 

 paste with sulphuric acid, and heated in a glass tube, produced an 

 etched ring just above the charge in the tube, indicating the 

 presence, of fluorine. Fused with borax, the mineral dissolves 

 into a clear glass, unless there is an excess of the powder. 



The powdered mineral is almost wholly taken up, by hydro- 

 chloric and by nitric acid, without sensible effervescence, forming 

 a porter-colored solution, from which ammonia precipitates the 

 characteristic bulky white precipitate of hydrated triphosphate of 

 lime. 



SEEOND SERIES, VOL. XXII, NO. 64. — JULY, 1856. • 13 



