ORDH VI. HEMI-PRISMATIC AUGITE-SPAK. 279 



must be remarked here, that the greater part does not be- 

 long to the genus Augite-spar. The passages demonstrate 

 that there are varieties of Asbestus belonging to the pre- 

 sent species, and moreover there are crystallised varieties, 

 of common Hornblende, consisting in their interior or ter- 

 minating on their ends in decided fibres of Asbestus in 

 a parallel position. This is also the case in certain va- 

 rieties of the preceding species ; and we are led to con- 

 clude that the term Asbestus itself rather expresses the 

 state of aggregation of several, than the substance of a 

 distinct mineral. Asbestus in general has been divided 

 into Amiantus, which consists of highly delicate fibres, often 

 thinner than a hair, longitudinally cohering with each 

 other, and easily separated ; into common Asbestus, relating 

 to coarser varieties, more firmly cohering, and yielding 

 splintery fragments ; into Rock-Cork , in which the particles 

 are aggregated in a loose felt-like texture, no longer recog- 

 nisable, or to be separated from the rest ; and into Rock- 

 Wood or ligneous Asbestus, in which a texture of the pre- 

 ceding kind, only more close, and resembling membranes, 

 assumes the general appearance of wood. Green Diattage or 

 Smaragdlte has been found (HAIDINGER, Trans. Roy. Soc. 

 Edin. Vol. X. p. 127.) in some cases to consist of laminae of 

 hemi-prismatic Augite-spar, with faces of composition pa- 

 rallel to Pr + co, in others of the same alternating with 

 laminae of paratomous Augite-spar, both often of bright 

 green colours. This kind of composition of the two species 

 is frequently found also in black varieties. 



Among the varieties of this and the preceding species, if 

 compared with each other, we are struck with the perfect 

 analogy of certain varieties distributed as it were in paral- 

 lel series. Augite and Hornblende, Sahlite and Actinolite, 

 Diopside and Tremolite, stand in these relations, and both 

 series terminate in their respective kinds of Asbestus. 



2. Of the following analyses, three have been published 

 by BONSDOEF, the fourth by VAUQUELIN : 



