80 



MINERALOGY. 



Siberia and from Lake Superior, the silver in crystals from Kongsberg 

 and from Freiberg, the suite of specimens of gold from Merionethshire 

 and other British localities, two unique nuggets of crystallised gold from 

 the Maclvor Diggings, in Australia, and one from California, are espe- 

 cially worthy of remark. Besides these, will also be seen native foil 

 of silver and of gold : moss-like filamentary aggregations of copper 

 and of silver; nuggets, and washed grains of gold, and specimens of 

 all these metals, in which a simple crystalline form, by being repeated 

 or prolonged along particular axes has built up dendritic, ramose, capil- 

 lary, and other singular kinds of structure. Among the specimens of 

 gold and of electrum, or argentiferous gold rich in silver, from Tran- 

 sylvania, are some worthy of notice from the sharpness of their crystal- 

 line forms. Native lead from Sweden, and a crystalline nugget of 

 platinum containing metallic iron and presenting magnetic polarity, 

 given by H. I. H. the Grand Duke of Leuchtenberg, are exhibited in 

 Case 2f. The rhombohedral series of metals includes an isomor- 

 phous group — the Arsenoids — namely, Arsenic, Antimony, and 

 Bismuth, with which its crystalline form, rather than its chemical 

 analogies, associates the rare native element Tellurium. 



Next to the metals are arranged the Metalloids, a section including Sectioi 

 the carbon group and the sulphur group. In the former, elementary Metallplf 

 Carbon is illustrated in its two allotropic mineral forms : Diamond and 

 Graphite. Of the Diamond, a large and extremely choice series of 

 crystals is exhibited, together with models of the most famous for their 

 size and history of the specimens of this, the hardest and most resplen- 

 dent of gems. Specimens of the diamonds of South Africa are ex- 

 hibited with the rocks in which they are found. 



Of Sulphur, the vast yellow crystals are among the most splendid 

 of the mineral productions of the earth. The glazed end of Case 1 

 contains specimens belonging to this division, of extraordinary size 

 and beauty. 



Division II. Compounds of the Arsenoid and Thionid Elements. 



Leaving the native elements, we enter upon minerals which are the 

 products of the chemical combination of the elements with each 

 other; but the transition is not an abrupt one. The alloys, or mix- 

 tures of metals of one and the same group, were associated in the 

 first division with the metallic elements that compose them. But 

 where metals belonging to distinct chemical groups are combined, they 

 cannot be classed with the free elements. Such are the combinations 

 of Arsenic, Antimony, and Bismuth with metals of other groups, and 

 the Arsenides, Antimonides, &c. accordingly take their places as the 

 first section of Division II. and will be found arranged in the first 

 three compartments of Case 3. 



Next in order to these are placed, as a second section of Division 

 II., the compounds of metals with the "thionid elements;" and 

 accordingly the Sulphides, Selenides, and Tellurides are displayed in 

 Cases 3d to 6g. 



