278 PHYSIOGRAPHY. CLASS u. 



certain kinds of Asbestus, comprehend far the greatest 

 number of varieties belonging to the present species. Horn- 

 blende differs from the rest chiefly by its dark, blackish, or 

 greenish colours, and is distinguished into three subspecies, 

 lasaltic Hornblende, common Hornblende, and Hornblende 

 slate. The first contains black imbedded and perfectly 

 cleavable crystals; the second refers to those imbedded 

 crystals in which cleavage is not so easily obtained ; it in- 

 cludes besides all implanted crystals and massive granular 

 or columnar varieties, except such as are black and easily 

 cleavable, and which have been distinguished from the rest 

 by the name of Carinthine. Hornblende slate compre- 

 hends compound or even mixed varieties, consisting of con- 

 fusedly aggregated columnar particles of composition, and 

 possessing a slaty fracture. Actinolite includes the green 

 varieties, frequently in acicular crystals, and has been sub- 

 divided into common, glassy, asbestous, and granular Actino- 

 lite. The varieties of the first subspecies are almost all 

 paratomous Augite-spar, and have been mentioned in the 

 preceding species. Glassy Actinolite contains crystals and 

 columnar compositions of a green colour ; asbestous Actino- 

 lite refers to capillary crystals and very thin columnar 

 compositions, of other colours than white ; granular Acti- 

 nolite comprehends grass-green varieties, whose composi- 

 tion is granular. The varieties of Tremolite, similarly 

 subdivided into subspecies, differ from the preceding ones, 

 particularly by their pale green, grey, or white colours. 

 Common Tremolite occurs in crystals, and in massive varie- 

 ties of columnar compositions, which possess low degrees of 

 transparency. More transparent varieties in similar com- 

 positions, consisting of thin individuals, are called glassy 

 Tremolite; asbestous Tremolite forms masses of very thin, 

 capillary crystals, exactly like asbestous Actinolite. Cala- 

 mite, which has but lately deen discovered, is an asparagus- 

 green, translucent variety in imbedded crystals, in a kind 

 of serpentine. Asbestous Actinolite and asbestous Tremo- 

 lite form a passage into Asbestus, of which, however, it 



