OF CENTRAL CANADA PART I. 



11 



The Tetragonal System This includes, principally, square-based 

 prisms and pyramids, and their combinations. Figures 8 to 9 are ex- 



Fio. 



FIG. 8 a. 



FIG. 9.* 



FIG. 9. 



amples of Tetragonal crystals. Amongst minerals, Copper Pyrites, 

 Tinstone, Rutile, Anatase, Zircon, Idocrase, Scapolite &c., may be 

 cited as belonging to the group. 



The Hexagonal System. Regular six-sibed prisms (Fig. 10, and 

 pyramids (Fig. 11), combinations of these (Fig. 12), three-sided prisms, 

 rhombohedrons (Figs. 13 and 14), and scalenohedrons (Fig. 15) ; are 

 included under this system. Graphite, Red Silver Ores, Cinnabar, 

 Specular Iron Ore, Corundum, Quaftz, Beryl, Tourmaline, Apatite 

 or Phosphate of Lime, Phosphate and Arseniate of Lead, Calcite, 



FIG. 13. 



FIG. 14. 



FIG. 14. 1 



FIG. 15. 



Dolomite, and Carbonate of Iron, are some of the principle minerals 

 which belong to it. 



The Rhombic System This system includes right-rhombic prisms, 

 rectangular prisms, rhombic octahedrons, &c., and their combinations. 

 Fig. 16 is a rhombic prism ; Figs. 17 to 21 represent other crystals of 



