. Annals of Philosophy. 242 Mr. Levy on a neio Mineral. [April, planes is 137° 5'', and that of the base on one of the lateral planes 94° 3'. Sphene presents in the series of its secondary forms many oblique rhombic prisms, the lateral planes of which are produced by modifications either on the lateral edges, two of the sides of the base, or the lateral angles ; and the base is, either the base of the primary or some secondary plane produced by a decrement on the angles a or o. None of these secondary oblique rhombic prisms that I have observed, nor any of those mentioned by Mr. Rose in the ex
. Annals of Philosophy. 242 Mr. Levy on a neio Mineral. [April, planes is 137° 5'', and that of the base on one of the lateral planes 94° 3'. Sphene presents in the series of its secondary forms many oblique rhombic prisms, the lateral planes of which are produced by modifications either on the lateral edges, two of the sides of the base, or the lateral angles ; and the base is, either the base of the primary or some secondary plane produced by a decrement on the angles a or o. None of these secondary oblique rhombic prisms that I have observed, nor any of those mentioned by Mr. Rose in the excellent paper on sphene, he has published at Berlin, have their planes inclined at the same angles as those of the primary of the substance I am describing. The secondary oblique prisms of this substance do not either in their measurements correspond with any of the oblique rhom- bic prisms of sphene. I have also tried whether I could not deduce by some law of decrement, the form of this new sub- stance from the primary of sphene, and I have found it was not possible without assuming very complicated laws. I believe, therefore, I am entitled to consider it as a new species. Mr. Heuland has proposed to me to call it Turneiile, from the name of the gentleman in whose collection it was first noticed as a distinct species. This tribute is certainly well due to Mr. Tur- ner, who has undertaken with so much readiness and liberality the publication of a detailed description of his most valuable collection. This new substance is very scarce, and besides the specimen where I have observed it, Mr. Heuland knows but one more in England. I could only detach a single crystal of it, and, therefore, could not attempt to determine its specific gravity, or to have it analysed. I hope the observations I have made may induce some others to examine the physical and chemical pro- perties of this substance, should they be able to procure it, and it is partly for this motive I publish them now. The
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