252 PHYSIOGRAPHY. 



Heavy Spar. 



gles truncated. P on = 127 5' 13". (emoussee, H.) 

 Fig. 231. The same, with the planes o enlarged, o on o 

 = 105 49' 34". (unitaire. H.) Fig. 232. d on u = 

 160 41' 39". u on w=116 38'. (bino-bisunitaire. H.) 

 Fig. 233. e?onZ=163 2' 22". (soussextuple. H.) Fig. 

 234. Mon*=15426' 52". z onz=110 25' 38". o on 

 z = 135 39' 58". (entouree. H.) Fig. 235. M on &= 

 129 13' 54". , k on o = 142 8' 47". (sexdecimale. H.) 

 Fig. 236. (sousquadruple. H.) Fig. 237. (triplante. H.) 

 Fig. 238. c on o = 166 46' 49 r/ . M on c=133 31' 

 31". (diplonome. H.) 



Cleavage. M and T perfect. The latter commonly 

 more easily obtained, the former sometimes interrupted. 

 Cleavages are also visible parallel with the shorter diagonal. 

 Fracture conchoid al } seldom observable. Surface in a few 

 examples only, faintly streaked. The same faces which in 

 certain modifications are rough, in others are perfectly 

 smooth, while the reverse takes place in other faces ; so 

 that they do not constantly present the same appearances. 



Lustre vitreous, inclining to resinous. Color white, prev- 

 alent, inclining to yellow, grey, blue, red or brown. Streak 

 white. Transparent . . . translucent. 



Brittle. Hardness =3-0 . . . 3-5. Sp. gr. =4-446. 



Compound Varieties. Globules, both imbedded and 

 implanted, also reniform shapes : surface drusy, uneven 

 and rough ; composition either lamellar, generally imper- 

 fect or columnar, the latter often very thin. In the reni- 

 form shapes, the curved lamellar particles of composition 

 consist of imperfectly straight lamellar, or of columnar ones. 

 Massive : composition as in the imitative shapes, more fre- 

 quently the distinctly straight lamellar masses are aggregated 



