On Metallic Minerals. 37t 



It resists the knife, hut is very brittle, almost friable. It is 

 powerfully magnetic, but not with polarity; colour of 

 powder, black ; specific gravity, 4-9. In nitric acid it 

 effervesces at first considerably, owing to the carbonate of 

 Jinjc between its laminae. Jk'fore the blow-pipe it decre- 

 pitates like galena, which it more resembles in appearance 

 than any ore of iron I every saw before, after which it seems 

 to burn for an instant; in other respects its blow-pipe 

 characters are the same as the other magnetic ores. 



This is au excellent ore, as it bears its flux with it, and 

 would [)rouably yield G5 per cent. 



2d. — Colour, brownish or yellowisij grey; opaque; 

 structure, fine grained; fracture, uneven; lustre, glim- 

 uicring, resinu metallic j yields to the knife, though not 

 easily, and affords a yellowish powder under the hammer; 

 s{iecific gravity, 3-^; not magnetic even after roasting on 

 charcoal. In the interior flame of the blow-pipe it forms, 

 like the garnet, a black globule which is slightly magnetic. 

 It contains crystals of garnet and iron; the latter are 

 always some modification of the octohcdron, the former 

 arc as usual dodecahedral. It is much mixed up with 

 carbonate of lime, as its free effervescence in acid evinces, 

 with borax it gives a glass coloured by iron. 



'Ibis I consider to be amorjihous garnet, a dark reddish 

 brown variety of u hidi is aUo met with. 



The crystals of garnet are sometimes of a red, at others 

 ol ii brown colour, but it is generally so intense aa to 

 render the crystals nearly opacjue. 



I have only one more ubservution to make on this bed, 

 viz. that by u bpecies of des(]uamation on the thin edges of 

 the lamiiiiv and along many of the lines of cleavage of the 

 calcareous spar a peculiar feathered ajjpearance i» given U> 

 njany u( the chistors of its cry.ilalj*, which, moreovff .i.-n.-. 



