188 Scientific Intelligence — Mineralogy. 



conglomerate. The copper is sometimes pure, and sometimes 

 mixed with silver ; silver occurs in spiculre and grains, imbedded 

 in the coppei', or crystallized in angular globules, adhering to the 

 surface of the mixture of copper and silver. Veins of pure silver 

 traverse masses of copper containing not more than from r oV^ ^^ 

 To'tf ^^ combined silver, and would thus seem to have been formed 

 by segregation. Metallic silver is abundantly disseminated in the 

 amygdaloidal rock in grains, which are sometimes as large as peas. 

 Among the curious features of the aniygdaloidal trap in question, 

 may be mentioned the occurrence of large veins of datolite, three 

 feet in thickness, in which the crystals of datolite contain small 

 scales of pure copper. Veins of prehnite, three or four feet thick, 

 are also met with in the trap, and these likewise contain numerous 

 spiculje and scales of pure copper. An erratic block of copper, 

 weighing about three thousand pounds, was found, on conglomerate, 

 near the river Ontonagon, and was probably derived from the ser- 

 pentine of the He Boyale, which is situated about forty miles to the 

 north. — (L'lnstitut, No. 584.) 



11. Cubane. — This mineral was first distinguished by Breithaupt 

 (Pogg, Ann, 59, p. 353). It has a metallic lustre, and its colour 

 varies from white to brass yellow ; its streak is black; the cleavage 

 cubic and pretty distinct ; the /rafhfrc flat conchoidal, or uneven ; 

 hardness equal to that of fluor-spar; brittle; specific gravity 

 = 4"026 to 4'042. Before the blowpipe it fuses easily. The cu- 

 bane has been lately analysed by Scheidhauer {Poggendorff' s An- 

 nals, vol. Ixiv., p. 280', and the following is its composition ; — 



Sulphur, .... 34-78 



Iron, .... 42'51 



Copper, .... 22-96 



Lead, .... trace 



100-25 



The locality of this mineral (which -n-as originally obtained, by 

 way of London, from the island of Cuba) is now ascertained to be 

 Bacui-anao, about seven English miles from the Ilavannah. 



12. Diamonds in the Matrix from Brazil ; and Black Diamond, 

 of unusual hardness, from Borneo. — LomonosofF has informed 

 the French Academy of Sciences, that diamonds occur in the fixed 

 rock in the so-called Itacoluniite of Brazil, on the left bank of the 

 Corsego des Rois, on the Serra da Grammagoa, forty-three Portu- 

 guese miles to the north of the town of Tijiicco or Diamantina. 

 Diamonds have be'*n obtained there, for some years, by blasting 

 the rock, then breaking it to pieces, and washing it. Several un- 

 doubted specimens of diamond in the matrix, brought home by Lom- 

 onosofl", were exhibited to the Academy. At the same time, a 

 black mineral was shewn, which Diard had obtained in Borneo, and 

 which is harder than diamond. At the request of the Academy, a 

 ?kilful lapidary endeavoured to cut it ; but, after twenty-four hours' 



