24>4 Mr Haidingers Account of the Specific Gravity 



These two varieties are very remarkable for their specific 

 gravity, which is equal to that of the hemi-prismatic fel- 

 spar, while their form is tetarto-prismatic. The difference 

 in their specific gravity from albite, and some differences in 

 the forms, render it very probable, that they will be found to 

 belong to a distinct species of the genus felspar. They oc- 

 cur not unfrequently in simple crystals. 



*50. Common Felspar of Werner, from Baveno, the red nearly 

 opaque variety, cleavable with the greatest facility, but only in one 

 direction, 2.392 



*5l. A variety in very thin lamellar compositions, pale reddish- 

 white, locality unknown, 2.423 



*52. Thicker Lamellae, of another kind, much resembling the 

 former, 2.425 



*53. Fragments of Crystals, yellowish- white, nearly opaque, said 

 to be from Elba, associated with the prehnite, No. 19. 2.445 



The low degrees of specific gravity, and the highly per- 

 fect cleavage observable, almost exclusively of the rest, pa- 



Pr 



rallel to— — (-P of Haiiy,) render it extremely probable that 



these varieties will also form a distinct species. We are yet, 

 however, much in want of decisive observations, particularly 

 in respect to the regular forms. The degrees of transpa- 

 rency are very low, the varieties being scarcely translucent 

 on the edges. 



64. Scapolite, a single crystal, white, translucent, from Pargas 

 in Finland, 2.724 



66. Paratomous Augite-spar, a variety resembling Sahiite, of a 

 grass-green colour, and easily cleavable, from the Bacher mountain 

 in Lower Stiria, 3.234 



56. Mussite, from Piedmont, in large laminae, of a yellowish- 



grey, compound in the direction of Pr+ od, 3.254 



57. Pale-grey Augite, (a variety frequently mistaken for bron- 

 zite,) showing faces of composition. It is^engaged in Saussurite, 3.256 



58. Augite, a wax-yellow, granular variety, associated with liver- 

 brown garnet, from Schwarzenberg, Saxony, 3.278 



59. Faasaite, deep leek-green, an isolated twin-crystal from 

 Fassa, 3.328 



60. Omphacite, leek-green, translucent, showing bright but in- 

 terrupted faces of cleavage, from the the Saualpe, Carinthia, 3.329 



61. Mussite, very pale ash-grey, in large individuals, from the 

 Tyrol, 3.350 



