148 ANNALY9IS OF 



adheres to the granite, and breaks with ease into ir- 

 regular fragments, whose sides are slightly changed 

 or soiled, as we so often observe in the trap rocks. 

 In the other fracture, the rock is extremely tough, 

 presenting a very fine scaly texture, of a bluish black 

 colour, opaque, excepting on the edges of the frag- 

 ments, and enveloping as a base, numerous small im- 

 perfect crystals, of a dark green colour ; sometimes 

 also, though rarely, fragments of granite are also con- 

 tained in it. By exposure to the air, the basis be- 

 comes of a light dirty olive green colour, whilst the 

 crystals assume an ochery appearance. Examined, 

 when in minute fragments,with apowerful microscope, 

 it presents a confused mass of silvery particles. I was 

 not able to ascertain with this instrument, if it con- 

 sisted of more than one mineral species. It feebly 

 attracts the magnet. Before the blowpipe, it fuses 

 into a black globule, whose fragments, when viewed 

 by transmitted light, are of a dark green colour. 

 As a part of the rock, which encloses these veins, has 

 lately been removed by blasting, I collected a consi- 

 derable quantity of their substance, and on breaking 

 it, I succeeded in obtaining some perfect crystals of 

 the dark green substance above mentioned, which on 

 examination, proved to be Pyroxene, or augite, pre- 

 senting the well known form the triumtaire of 

 Hauy, so abundant in the lavas of Auvergne, Italy, 

 Sicily, &c. The hemitrope or made of the same 

 form also exists in it. 



These veins appear to be almost entirely com- 



