84 GEOLOGY OF THE SON VALLEY, ETC. 



notwithstanding the alteration of the minerals. The original augites 

 had crystallised at an earlier stage than in T y ¥ for many of them show 

 idiomorphic outlines. Portions of felspar prisms are, however, inter- 

 grown with them, showing that crystallisation of the felspar had com- 

 menced before that of the augite was completed. This augite is, 

 however, entirely changed to uralite which exhibits the most beauti- 

 ful pleochroism. 



The sharp-angled cleavage with its want of parallelism to the 



prism faces, so characteristic of uralite, is ex- 

 Typical uralite pseudo- r 

 morphs after augite. hibited in several crystals. The substance of 



the hornblende is crowded with small inclusions the exact nature of 

 which it is difficult to ascertain. They give the crystals a somewhat 

 clouded appearance. Sometimes the sharp and w T ell-defined edge 

 of the crystal is surrounded by an additional narrow zone of chlorite 

 full of minute actinolitic needles, more or less irregularly oriented. 

 At other times, a fringe of hornblende needles has developed 

 in crystallographic continuity with a grain of 

 hornblende. uralite producing an additional growth of small 



prisms projecting into the saussuritised felspar. That they are an 

 additional growth and not the torn edges of the hornblende is made 

 clear in this case owing to the outline of the felspar which can still be 

 clearly followed, The present section shows several instances where 

 this is undoubtedly the true explanation. The felspars exhibit the 

 characters of labradorite, but they are saussuritised to an extent 

 quite comparable with the specimen T y ¥ . The usual chlorite- 

 epidote aggregates are typically developed. Ilmenite is mostly 

 altered to leucoxene, but sometimes cores remain of the unaltered 

 mineral. 



This uralite-diabase may be taken as the type of a very large 

 number of Bijawar rocks all presenting almost identical characters. 

 -J^,, collected by Mr. Oldham at Bhanni, is absolutely identical in 

 section. It is a little coarser grained in the hand-specimen. The 

 specific gravity is the same : 2*97. Such is also 7 y F , collected north 

 of Chakdehia, where it is clearly interbedded with the, slates. The 



( 84 ) 



