362 Scientific Intelligence. 



ter. It is intended to form a popular treatise, embracing all the Chemical, 

 Physical, and Natural History properties of Mineral Bodies, with an ac- 

 count of the various purposes in the fine and useful arts to which they are 

 applied. It will occupy one large volume 8vo. and will be illustrated with 

 numerous plates, representing the internal structure, and the external form 

 of crystallized bodies. In the introduction it is proposed to give a popu- 

 lar account of all the discoveries" 'that have been made during the last ten 

 years respecting the optical and physical structure of minerals, and a de- 

 scription of various new methods and instruments for examining and dis- 

 tinguishing the precious stones and other mineral bodies. 



34. Mohsite, a New Mineral Species. — Form rhombohedral. One of its 

 crystals is represented in Fig. 10 of Plate IV. . The terminal edges of the 

 fundamental rhombohedrons R, or the incidence of P on P over b' are 

 = 73°43'. The other measurements are, 



b on a' = 112°30 b' on b' === 96°22' 



b' — a' = 129°39 e' — e' = 64°0' 



e' — a'= 101°42 d? — d? — 142°14 



P — d 2 = 157°10 d? — d 1 = 99°22 



The surface is brilliant, with the exception of d' and d 2 , which are less 

 shining ; cleavage apparently none ; fracture conchoidal ; opaque ; colour 

 iron-black; lustre bright metallic; no action on the magnetic needle; 

 brittle ; scratches glass very easily. The crystals are flattened between the 

 faces a' and its opposite, so as to produce a tabular appearance. They are 

 small and implanted on quartz, mixed with a little chlorite, probably from 

 Dauphiny. 



Mr Levy, to whom mineralogy is already so much indebted for the 

 establishment of new species, has given the above description of one which 

 he discovered among Mr Heuland's rare minerals, and called it, at his sug- 

 gestion, Mohsite, in honour of Professor Mohs. Mr Levy observes that 

 this new species has almost identically the same form as Eudialyte, as de- 

 scribed by him in the Edinburgh Philosophical Journal for Jan. 1825, the 

 fundamental form of the latter being a rhombohedron of 73°40'. He de- 

 scribes likewise twin-crystals, which are said to be formed by two indivi- 

 duals with parallel axes, but not reversed for 180°, but only for 30° or 90°. 

 No figure being given, it would be unavailing to attempt here any expla- 

 nation of the fact stated, upon the supposition that the otherwise general 

 law also takes place in the present instance. Mohsite very much resembles 

 Crichtonite, and axotomous iron-ore, but is distinguished immediately by 

 its greater hardness, and want of cleavage perpendicular to the axis. 



35. Analysis of Hctepozite* This mineral was found at Thoreaux, in Haut 

 Vienne, in France. Part of it was tender, and part hard. The tender 

 part gave a fine violet powder, and the hard part a greyish and sometimes 

 a yellowish powder. The specific gravity of the violet part was 3, and in 

 a slight portion M. Vauquelin found it to consist of— 



