Table Lands of South India. 317 



tinguished by the grains not coming off in minute lamina by 

 the point of a pen-knife. 



Fracture. — Irregular and granular. 



Cleavage. — Into lamina generally, not extensive, nor very 

 thin. 



Structure. — Minute, requires a lens to see it, exactly like 

 that of black granite, the crystals of hornblende being plainly 

 visible. 



Fresh fracture, like black granite. 



Weathered surface more like schistose sienite, by the grains 

 of felspar becoming more easily visible. 



Differs from schistose sienite, only in containing more 

 hornblende. 



Is found embedded in granite, and also in beds in the 

 schistose series. 



Greenstone. 



This absurd term for a rock almost always black or brown, 

 appears to have been borrowed by Werner from the Swedes, 

 by whom it was applied to a rock really green, formed of horn- 

 blende and mica, with some particles of quartz, (Pinker ton* s 

 Petrology.) The name has been very loosely applied by writers 

 on geology ; but the correct definition may be, a confused 

 aggregation of crystals of hornblende intermixed with a few 

 crystals of dark-coloured felspar: the latter being in small 

 proportion. It has a general dark hue or blackish appearance, 

 in which it differs from sienite, which is speckled. 



Fracture. — Imperfectly granular and irregular, cleavage 

 none. The weathered surface has a rusty brown appearance. 

 Occurs as beds among the schistose series. 



Globular Greenstone. 



The characters the same as greenstone, except that the 



blocks even of 12 feet in diameter, have a perfect concentric 



lamillar structure, by which it exfoliates into pieces about an 



inch or two in thickness, having exactly the appearance of a 



2 s 



