MENACANE, AND ITS ORES. |35 



also sufficiently distinguishes it from iserine and iron sand *. 

 Being found in company with fragments of rutile of a dark 

 colour, the lattethas by most been confounded under the 

 same denomination ; but the red colour of the rutile, joined 

 to its perfectly foliated fracture, with a two-fold cleavage, 

 intersecting each other at right angles, and the thence re- 

 sulting cubical fragments, distinguish it sufficiently from 

 nigrine. 



The present description is taken from a specimen I had 

 the pleasure of receiving from Professor Jacquine the 

 younger, of Vienna. 



CHEMICAL CHARACTERS. 



The nigrine is infusible per se by the blow-pipe : but, with Chemical cha- 

 the assistance of borax, it melts to a transparent, hyacinth ractersof 

 red bead: to acid of sugar, it readily yields its medac con- "'S"ne. 

 tents, which furnishes the characteristic precipitate of this 

 genus. Klaproth and Lampadius have given us the consti- 

 tuent ingredients, 8 or 9 per cent, menac calx, and 2 or 1 

 calx of iron. It is probable, however, that the proportion 

 of menac calx is over-rated ; it appearing evident, from the 

 description accompanying the analysis, that there had been 

 no care taken to select the nigrine from the grains of rutile 

 which accompany it. 



GEOGNOSTIC OCCURRENCE. 



The nigrine has been hitherto found only at Ohlapian, in Geo t' 

 Transylvania, in alluvial hills, consisting of yellow sand, in- currScJir" 

 termixed with fragments and bowlders of granite, gneiss "^'S^ine. 

 and mica slate, and from which gold is obtained by washing! 

 This gold is the purest found in Transylvania ; a circum- 

 stance sufficiently indicating, that it belongs to a different 

 and, consequently, earlier formation, than the usual Tran. 

 sylvanian native gold, which occurs there in clay por- 

 phyry, grey wacce, and grey wacce slate, and belongs to the 

 brass yellow variety, from the considerable alloy of silver 

 which it contains. In these stream works, the nigrine is 



* Qenuine iron sand must not be confounded with magnetic iron 

 pre in a sandy f^rm^ which usually passes under that name. 



«■ , obtained 



