42 PHYSIOGRAPHY. CLASS I, 



P =r { l ^ ^ } ; 108 6' ; 126 58'. Inclina- 



tion of the axis = 14 20' in the plane of the 

 long diagonal. Vol. I. Fig. 41. R. G. 



a : b : c : d = 3-920 : 3-090 : 2-629 : 1. 



Simple forms. P o> (6) ; ? (P) = 101 35' ; 



-696'- +^ r / 



- 



-- 



l - - 128 4' 



Pr (o) = 69 IT ; Pr + <x> (M). 

 Char, of Comb. Hemi-prismatic. Inclination of 



P OD to ?r + QD = 104 20' ; of P QD to 



P + oo = 99 23'. 

 Combinations. 1. P oo. P -f oo. Sim. Fig. 44. 



3. P QD. . Pr. P + QD. Pr + QD. Pr -f oo. 



4 P - a,. L^Z^ L r . ?. Pr. - ?_ r . 

 222 2 



P + x. Pr 4- CD. Fig. 52. 



Cleavage. P OD, perfect ; P + oo, distinct, 

 though less perfect than P QD ; sometimes 



traces of . Fracture conchoidal. Surface 



generally smooth ; nearly the same in all the forms. 



Lustre vitreous. Colour, several shades of green, 



passing into white. Streak white. Semi-trans- 



