ALUMINA. 



365 



KYANITE. 



[From tlic Greek mamg, hbw ; on account of its blue colour ] 



Cyanite. CfcawZarerf. — Disthcnc. Hainj a.nd Bcn<lanf. — Cyanite, or Scsquisilicate of Alumina, Tkmiison.— 

 Prismatic Kyanite. Jamesmi. — Prismatisrhcr Disthpn-Spath. Mohs. — Kyanite. Pkillips, S/upani and 

 Dana. — Sapparc. Saussurc. 



Fig. 381. Description. Colour white, grey, blue, and bhiish-green. Streak 



white. It occurs regularly crystallized ; also massive and disseminated- 

 Primary form a doubly oblique prism. Fig. 381. P on M 93° 15'; 

 P on T 100° 50' ; M on T 106° 15'. Cleavage distinct parallel with 

 M and T ; difficult parallel with P. Fracture uneven. Lustre pearly. 

 Varies from transparent to translucent. Brittle. Hardness from 5.0 

 to 7.0. Specific gravity from 3.50 to 3.70. Before the blowpipe, 

 even its powder is infusible, and it remains unaltered in very higli 

 degrees of temperature ; with borax, it fuses with great difficulty into 

 a transparent colourless glass. It is not acted on by acids. 



Varieties. Kyanite. This includes those specimens which have a blue colour. 

 RhcBtizite is the white or somewhat reddish variety, occurring in aggregated masses. 



Composition. Kyanite — Alumina 64.30, silica 34.33 {Arfwedson). Alumina 67.80, silica 

 31 .60, lime 0.20 {Beudant). 



Geological Situation. This mineral occurs exclusively in primitive rocks, and especially 

 in the granitic white limestone. 



localities. 



New-York County. Kyanite has been found in loose masses of granite near the city.* 

 They are usually, however, of an inferior quality. 



Orange County. Dr. Horton refers to some localities in the towns of Warwick and 

 Monroe, but these minerals are probably more nearly allied to bucholzite than to the present 

 species. 



In Massachusetts, there is a fine locality of kyanite at Chesterfield, where it is associated 

 with garnet in mica slate. 



In Pennsylvania, fine specimens of kyanite have recently been found in Delaware county. 



* Cozzens. American Journal of Science. X. 200, 



