314 On the formation of the . 



grains of various sizes of pure hornblende, without any admix- 

 ture of other minerals. 



Colour. — Shining deep coal black; sometimes a brownish 

 black. 



Crystals. — Imperfectly foliated; longitudinally deeply mark- 

 ed or lined, sometimes striated. 



Fracture. — Uneven ; smell none. 



Streak. — Whitish. 



Bruise. — Black, very little whitish. 



Weathered surface. — Brownish ; sometimes very little de- 

 composed, sometimes decomposed* into a yellowish sub- 

 stance of an ochrish appearance, but with the striated surface 

 of the crystals still visible. 



Melts before the blowpipe into a black frit, or dull glass, 

 with strong intumescence; sometimes with difficulty into a 

 deep black perfect glass without intumescence. 



Called hornblende rock by MacCulloch, common horn- 

 blende by Jameson, found embedded in granite rock ; also in 

 beds in the schistose series; also embedded in situ in kunkur ; 

 sometimes contains crystals of green Augite. 



Is found four miles east of Oossor, intersected with thick 

 veins of crystalline white quartz and white felspar, giving to 

 the mass which it forms, (a small hill,) a curious pyebald 

 appearance. 



Black -Granite. 



Colour. — Greyish black, nearly quite black when polished ; 

 composition of black hornblende in the largest proportion, 

 with grains of quartz and felspar. 



Fracture. — Irregular, sometimes imperfectly conchoidal, 

 perfectly granular, but generally like fine-grained granite. 



Structure. — Of perfect crystalline grains of hornblende, 

 which to a lens shew the characters of hornblende imperfect- 



* It is doubtful if it is decomposed, for I have lately got crystals 

 containing the yellow ochre inside of them. 



