PHYSIOGRAPHY. 



Heavy Spar. 



249 



companied by small masses of Calcedony, Garnet, green Horn- 

 blende, Talc and Magnetic Iron-Ore the aggregate being en- 

 veloped by a ferruginous clay, and existing in an iron mine adja- 

 cent to the Hay Tor granite quarries, in Devonshire. The for- 

 mation of these crystals is quite inexplicable according to the 

 known laws of pseudomorphism. 



HEAVY SPAR. Prismatic Hal-Baryte. 

 MOHS. 



Primary form. Right rhombic prism. M on M'=101 

 42'. 



Secondary forms. 



Fig. 223. 



Cheshire, (Conn.) 

 Fig. 229. 



De Rome, Puy de Dome. 



Fig. 231. 



Fig. 230. 



x M 



