1 87 1.] Mineralogy. 131 



remember that we are in possession of a large body of evidence tending to 

 show that the diamond is probably of vegetable origin, or has at least been 

 formed by the wet way, and that, therefore, its occurrence is not to be expected 

 in an eruptive rock, although the presence in such a rock may have 

 influenced its development. It may not be amiss to direct the attention of 

 diamond-seekers at the Cape to the probable occurrence of the substances 

 known as bort and carbonado in association with the true diamonds. These 

 minerals are, from their unattractive appearance, likely to be overlooked by 

 those who are absorbed in looking for the more precious gem, and yet they possess, 

 in consequence of their extreme hardness, a very high value for polishing 

 purposes. The black metallic-looking carbonado accompanies the diamond 

 in Brazil, where it was entirely overlooked until a comparatively recent date, 

 and we believe that it has already been found in South Africa. Whatever may 

 be the future prospects of the South-African diamonds-fields, it is certain that 

 we must henceforth register in our mineralogical text-books such parts of 

 the valley of the Vaal as Pniel and Hebron as important diamond-bearing 

 localities. 



In New South Wales the search for diamonds has also been prosecuted with 

 some measure of success, and according to Mr. John Hunt,* who has acted as 

 Manager of the Australian Diamond Mining Company's Works, there have 

 hitherto been found in the colony about 5500 diamonds, averaging one grain 

 each. He believes that an excellent clue to the presence of diamonds, there 

 and elsewhere, is afforded by the presence of a certain green mineral containing 

 phosphate of iron. The diamonds oT New South Wales are found, accom- 

 panying gold, in the alluvial drifts, and especially in the neighbourhood of 

 basaltic rocks. 



Some time ago we hinted that diamonds had been reported from Bohemia. 

 The report was circulated in many of the German and Bohemian journals, but 

 according to Professor Zepharovich,f it rests upon a very insecure basis. 

 Indeed, it appears that only a single stone has been found, and this under 

 conditions far from satisfactory. As is well known, the pyropes, or "garnets," 

 found in the sands of some of the Bohemian rivers are extensively cut and 

 polished for the purposes of the jeweller ; and it was among a number of these 

 stones at the polishing-works of Dlaschkowitz that the diamond in question 

 was found. That a diamond has been discovered among Bohemian garnets is, 

 therefore, certainly a fact ; but that it was derived from the same deposit with 

 the garnets is, at present, merely an assumption. When we remember that 

 diamonds are in daily use in the workshop for the purpose of boring the 

 garnets, a suspicion arises that after all the so-called " Bohemian diamond " 

 may be merely a stray stone from the lapidary's stock. At least it behoves us 

 to be silent upon the subject until we shall hear that diamonds have actually 

 been found in the garnet-bearing sands. 



More than twenty years ago the Italian mineralogist, Professor Scacchi, 

 described a new arsenical sulphide from the solfatara in the Phlegroean fields, 

 where it occurs in the form of minute orthorhombic crystals difficult of 

 measurement, but still sufficiently perfect to exhibit, in different specimens, 

 two distinct sets of axial relations, whence the mineral received the name of 

 Dimorphine. Dr. Kenngott has recently made some observations on the 

 crystalline forms of this so-called species,^ and finds that not only are the two 

 types of form closely related to each other, but that they stand extremely near 

 to the crystalline forms of orpiment. Dimorphine appears, therefore, to be 

 crystallographically nothing more than orpiment, but while orpiment contains 

 As 2 S 3 , it appeared from Scacchi's imperfect examination that dimorphine had 

 the composition of As 4 S 3 . Nevertheless, the specific gravity and the colour of 

 the two minerals are almost identical, and, on the whole, Kenngott is disposed 

 to lay aside Scacchi's formula, and to believe that dimorphine must be united 

 with the species orpiment. 



* Mining Journal, Nov. 12, 1870. 



+ Poggendorff's Annalen, 1870, No. 8. 



% Leonbard and Bronn's Neues Jarbuch fur Mineralogie, 1870, Heft 5, p. 537. 



