Ammonites or Ceratites from Oregon Bar, Middle Fork of the American River.
BY PROF. WM. P. BLAKE.
The specimen which I exhibit to the Society this evening, is from the collection of J. J. Spear, of this city. It was kindly loaned to me by that gentleman for examination. Not wishing to risk the specimen, by sending it to a paleontologist at the East, I had it photographed, and sent a copy to F. B. Meek, Esq., of Washington. It is not possible to determine from the specimen, whether these fossils are new or not, or even, whether they are Ammonites or Ceratites. They appear to be not unlike the fossils described by Dr. Trask, under the name of A. Chiceonsis, Proc. Acad. Nat. Sci. Cal.; but it is not safe to identify them, without the septæ can be clearly made out.
There are several casts in an argillaceous, somewhat micaceous slate. This locality is about 15 miles from Coloma. It is not certain, whether the specimen was taken from the slates in place, or broken from a loose mass.
Mr. Moore presented the following paper:
On Brushite, a new mineral occurring in Phosphatic Guano.
BY GIDEON E. MOORE, PH. B.
In the spring of the present year, I received through the kindness of Wm. E. Brown, Esq., of Mare Island, in this State, a specimen of a mineral discovered by him in a cargo of phosphatic guano, at Camden, N. J. The locality from which it was derived, is not known, and though letters of enquiry have been sent to the parties to whom the cargo was originally consigned, no reply has been received up to this date. The texture and appearance of the guano would, however, point to some one of the Caribbean Islands, and more particularly, to the Island of Sombrero, as its probable source. It is very probable that the mineral may be recognized among the crystallized products occurring in other guano deposits.
In the specimen in my possession, the mineral occurs filling seams in the guano, varying from ⅛ to ¼ of an inch in width. The matrix itself is of the variety known as rock guano. It possesses an oolitic structure and a brownish white color, interspersed with small spots of pure white.
The mineral is in the form of small but very perfect and brilliant crystals with a cleavage in the direction of their greatest length, nearly equal to that of selenite; the laminæ, being also slightly flexible, as in the case of the latter species. Hardness, 2.25 (Moh’s scale). Specific gravity, 2.208, (mean of two determinations). Color, yellowish white. Transparent. Lustre, vitreous splendent, inclining to pearly on the cleavage faces.