140 Mr HAIDINGER on the Natural-Historical 



bohedral Quartz, and emits lively sparks, if struck with steel. 

 Of the rest of the minerals generally occurring along with Dial- 

 lage, the most frequent are ; Garnet, of a reddish colour, inclining 

 to grey, lustre resinous, hardness 7.5, specific gravity 3.647 ; 

 likewise Talc and Kyanite. These species, if intermixed with 

 each other, constitute that rock which has been called Gabbro by 

 VON BUCH ; but the relative quantities of the ingredients not 

 being every where the same, 1 shall shortly mention those in 

 some of the most generally known varieties. 



The beautiful Verde di Corsica duro, almost entirely consists 

 of compact Saussurite, of different shades of bluish-grey, in 

 clouded delineations, containing small imbedded masses of green 

 Smaragdite, which is very nearly pure hemiprismatic Augite-spar. 

 Its specific gravity is 3.000 ; the face of composition is not 

 very distinct, and rather incohering, while the real cleavage, pa- 

 rallel to the faces of the prism, is more distinct, from the co-ex- 

 istence of which and the former the silky lustre is derived, 

 particularly if its varieties be cut and polished. It contains, 

 moreover, small masses of Talc, with delicate acicular crystals of 

 that variety of hemiprismatic Augite-spar, which has received the 

 name of Actinolite. 



The Saussurite, forming the paste of the Gabbro, from the Val- 

 ley of Saass, is greenish-grey, and nearly compact ; the Smarag- 

 dite which it includes, sometimes in masses of considerable di- 

 mensions, is mountain-green ; it presents very little lustre upon 

 the faces of composition, and almost no traces of cleavage. Yet 

 these varieties of hemiprismatic Augite-spar, seem to contain but 

 little heterogeneous matter, their specific gravity being 3.056. 

 The faces of cleavage, appear more distinctly, in certain veins of 

 perfectly pure varieties of the same species, which traverse in all 

 directions the larger masses of Smaragdite, with which, however, 

 they always remain in a parallel position. In this variety of 

 Gabbro, we likewise meet with particles of Garnet and Talc, con- 



