the Ores of Manganese. 128 



These are the most common, and at the same time the least 

 complicated of the varieties of the present species. 



4. (p r _2) 3 . (l-Pr) 3 . (Pr) 3 . P+l. P+co. (Pr+co) s . 



2 



(Pr + oc) 3 . Fig. 5. 



The 6th Figure represents the projection upon P oo, the 

 7th Figure the elevation upon a plane parallel to the short dia- 

 gonal of the prism P -f- GO. The hemi-prismatic character of the 

 species appears only in the disposition of the faces marked c. 



{j 



They form horizontal edges of combination with (Pr) 3 . These 

 crystals are from two to three lines in thickness, and some of 

 them nearly an inch long. 



5. Pr. (Pr I) 3 . Pr. P. P+l. P+co. (Pr + oo) 5 . 



(Pr+oo) 3 . (Pr+oo). 5 . Fig. 8. 



Small but very well pronounced crystals of this variety were 

 disengaged from the same specimen which contains the variety 4. 

 They were found in small drusy cavities, which were discovered 

 when the whole was broken up for analysis. The edges between 

 (Pr I) 3 and P+l are parallel to those between P+l and 

 (Pr+ oo) 3 . The faces of Pr, marked e in the figure, are rarely 

 observed in the crystals of this species. 



y 



Cleavage, Pr + oo highly perfect and easily obtained ; P + oo 

 also perfect, but less easily obtained; traces of Pr+oo, and of 

 P GO . Fracture uneven ; surface of the vertical prisms streaked 

 parallel to their common edges of intersection ; Pr streaked pa- 

 rallel to the edges of combination with P ; P GO parallel to 

 those with Pr. In general, the faces are smooth, and possess 

 pretty high degrees of lustre. 



Lustre, imperfect metallic. Colour, dark brownish-black, in- 

 clining to iron-black. Streak, reddish-brown. Opaque, in larger 



