PHYSIOGRAPHY. 129 



Pyromorpbite. 



M orM'ond' 150 00' PHILLIPS. 



M' on c' or M' on c" 131 45 



P on c or c" 138 30 



c' on c or c" - - 1 10 5 



Cleavage, traces parallel with M, also parallel with c. 

 Jracture imperfectly conchoidal, uneven. Surface, M al- 

 most always horizontally streaked, and often barrel-shaped, 

 or contracted at the ends of the prisms. P rough, and of- 

 ten excavated. 



Lustre resinous. Color, generally green or brown. 

 There is an uninterrupted series from various shades of 

 white, through siskin-green, asparagus-green, grass-green, 

 pistachio-green, olive-green, oil-green ; wax-yellow, honey- 

 yellow, orange-yellow; aurora-red, hyacinth-red; hair- 

 brown, clove-brown; pearl-grey and ash-grey. Streak 

 white, sometimes inclining to yellow. Semi-transparent . . . 

 translucent on the edges. 



Brittle. Hardness =3-5 . . . 4-0. Sp. gr. = 7-098, of 

 a green variety from Zschopau ; 6-831, of a brown variety 

 from Zimapan. 



Compound Varieties. Globular, reniform, botryoidal, 

 fruticose shapes; composition columnar; faces of compo- 

 sition rough, irregularly streaked, seldom smooth. Massive : 

 composition columnar, or granular ; the latter in most cases 

 strongly coherent. 



1 The green and brown varieties are separated by some mineralo- 

 gists into distinct species, without sufficient reason, however, inasmuch 

 as there are individuals whose properties form an uninterrupted series of 

 connexion between the two. 



2 Before the blow-pipe, on charcoal, it melts in the outer flame 

 globule, which crystallizes on becoming cold, and changes to a brown 



a 



