OHDER I. MACROTYPOUS LIME-HALOIDE. 95 



with R. The rest of the faces generally smooth, 

 and of nearly the same physical quality. 



Lustre vitreous, inclining to pearly in several va- 

 rieties. Colour white, seldom pure, generally 

 inclining to red or green. Various shades of 

 red, among which is a fine rose-red. Also green, 

 brown, grey, black, very often owing to foreign 

 admixtures. Streak, greyish- white. Semi- 

 transparent ... translucent. 



Brittle. Hardness = 3*5... 4-0. Sp. Gr. = 2-884, 

 a greenish- white cleavable variety from Miemo. 



Compound Varieties. Twin-crystals ; axis of 

 revolution perpendicular, face of composition pa- 

 rallel to one of the faces of K -f oo. Fig. 1 34, 

 from Piedmont. Sometimes variously repeated. 

 Implanted globules; botryoidal, fruticose, and 

 other imitative shapes : surface drusy and rough, 

 composition columnar. Massive : composition gra- 

 nular, of various sizes of indiv iduals, generally easi- 

 ly distinguishable, and often but slightly cohering. 

 The composition is often columnar, also of different 

 sizes of individuals. These compositions are again 

 variously compound, as the granular composition in 

 a coarser kind of granular composition, of which 

 the component particles may be easily separated, and 

 present an uneven surface. It occurs often in crys- 

 talline coatings upon other crystals, impressions, &c. 



OBSERVATIONS. 



1. It is difficult to find out in mineralogical works the 



