. Annual report of the regents of the university on the condition of the State Cabinet of Natural History and the historical and antiquarian collection annexed thereto. more easily than the preceding, and gives abubbly, semitransparent pearl. 3. Oligoclase, (natron spodumen.) Sp. gr. 2*61 to 2*69, and rarely2*70. One of the faces of cleavage presents very fine striae. It meltseasily, and gives a pearl free from bubbles, sometimes transparent,sometimes opaline, and sometimes like enamel. These differencesseem to be due to the proportions of lime which they contain. None of the three above descr
. Annual report of the regents of the university on the condition of the State Cabinet of Natural History and the historical and antiquarian collection annexed thereto. more easily than the preceding, and gives abubbly, semitransparent pearl. 3. Oligoclase, (natron spodumen.) Sp. gr. 2*61 to 2*69, and rarely2*70. One of the faces of cleavage presents very fine striae. It meltseasily, and gives a pearl free from bubbles, sometimes transparent,sometimes opaline, and sometimes like enamel. These differencesseem to be due to the proportions of lime which they contain. None of the three above described, are sensibly acted on by muriaticacid. 4. Labradorite. This sometimes presents a striated surface, like thepreceding. Sp. gr. from 2*67 to 2*73. It melts more easily than oli-goclase, and gives rise to a transparent or opaline pearl; but its mostdistinctive character is its solubility, when pulverized, in muriatic acid. Mr. Alger, in the supplement to his edition of Phillips Mineralogy,(page 420) gives a figure of a twin crystal of feldspar from Hammond,St. Lawrence county. It has smooth planes, is very perfect, and is oneof the simplest of the twin To the locality of crystallized albite, noticed in my Mineralogy, Imust now add the hemitropic form found by Dr. Emmons in the CoalHill mine, St. Lawrence county. Rep. on the Geol. 2d p. 366. 139 STELLITE.(Mineralogy of New-York, page 342.) The mineral from the trap region of Bergen, in New-Jersey, andPiermont, in Rockland county, New-York ; which I supposed to be thestellite of Dr. Thomson, has been the subject of some discussion. It is stated by Dana, (Mineralogy, 2d ed.,) that Mr. A. A. Hayes hasanalyzed the same mineral with quite a different result, as follows:Silica, 5598; lime, 35-12; soda, 6*75; potash, 0*60; alumina andmagnesia, 0-08; protoxide of manganese, ; water, (hygrometric)016;=993l. Dana adds that the large per centage of soda, and theproportion of silica and lime, would seem to ally the spe
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