132 Mr HAIDINGER'S Mineralogical Account of 



At Artzberg in Bayreutli also, it appears as the product of the 

 decomposition of the same substance, covering the surface of the 

 cavities left in quartz by the original rhombohedrons of the spe- 

 cies. 



The English localities of psilomelane are Restormel and Up- 

 ton Pine near Exeter in Devonshire, and Cornwall. 



IV. BRACHYTYPOUS MANGANESE-ORE. 

 Braunite. 



Brachytypous Manganese-ore, Haidinger, Edin. Journ. of Science, vol. iv. p. 48. 

 Brachytypous Manganerz, Lconhard, p. 759- 



Fundamental form. Isosceles four-sided pyramid. P 109 

 53', 108 39'. Fig. 18. 



a = VI. 94. 



Simple forms. P 00(0); P (P), Wunsiedel, Bayreuth ; 

 P + 2 (*) '= 96 33', 140 30', Fig. 17., Elgersburg, Thuringia: 

 (P+ I) 3 (z) - 144 4', 128 17', 154 25'. 



Char, of comb, pyramidal. 



Combinations. 1. P oo. P. Fig. 20., Wunsiedel. 



2. P. P + 2. Fig. 21., Elgersburg. 



3. P. (P+l) 3 . Fig. 22., St Marcel, Piedmont. 



4. P oo. P. P+2. Fig. 23., Wunsiedel. 



Cleavage, very distinct in the direction of the faces of P ; en- 

 tire forms of cleavage may be obtained from larger individuals. 

 Fracture uneven. Surface, P oo, possessing less lustre than P, 

 but even, and sometimes faintly streaked parallel to the edges of 

 combination with P ; P often a little" rounded ; P + 2 uneven, 

 rough and horizontally streaked ; the eight-sided pyramid 

 (P+ I) 3 smooth and even. 



