464 PHYSIOGRAPHY. CLASS n. 



straight, and generally small or even impalpable. 

 There is sometimes a second curved lamellar or gra- 

 nular composition, the faces of composition being 

 uneven or rough. Massive : composition as in the 

 imitative shapes; fracture even, flat conchoidal, un- 

 even. Pseudomorphoses in low, nearly regular six- 

 sided prisms, perhaps of prismatic Melane-glance. 

 Cellular. 



OBSERVATIONS. 



1. The varieties of Iron-pyrites, which belong to the 

 present species, are the Radiated Pyrites, the Spear Pyrites, 

 the Cockscomb Pyrites, the Hepatic Pyrites, and some varie- 

 ties of the Cellular Pyrites, as has been observed above. 

 The distinction among these subspecies depends upon the 

 shape and composition of crystals, and upon several acci- 

 dental circumstances. The crystals of lladiated Pyrites 

 are generally simple ones, not twins, and it occurs besides 

 in numerous imitative shapes and massive varieties, shew- 

 ing a columnar composition. Spear Pyrites is found only 

 in compound crystals consisting of two, three, or a greater 

 number of individuals, regularly grouped ; it does not pre- 

 sent any imitative shapes, and hardly any massive varie- 

 ties. Cockscomb Pyrites occurs both in simple and com- 

 pound crystals of a particular form, with indentations along 

 their edges, and a colour much inclining to green or 

 grey. The six-sided prisms commonly called crystals of He- 

 patic Pyrites, are pseudomorphoses, and often consist of 

 hexahedral Iron-pyrites. It is found in some imitative 

 shapes and massive, but generally the grain of the composi- 

 tion is impalpable, the fracture even or flat conchoidal, and 

 the colour greyish. That variety of Cellular Pyrites which 

 belongs to the present species, though disposed in regard to 

 its extraneous form, like that of hexahedral Iron-pyrites, 

 is produced by small crystals of a prismatic form. 



2. The mixtures of the prismatic and the hexahedral Iron- 



