84 MIDDLEMISS: GEOLOGY OF HAZARA AND BLACK MOUNTAIN, 



No. j|^ likewise stands alone as one representative of the 

 ultra-basic division of rocks. It is a crystalline-granular association 

 of olivine, partly altered along fissures into serpentine and iron 

 oxide, pale green augite, sometimes slightly crushed and schillerised 

 in places, and hypersthene (?) visible doubtfully in two places in the 

 rock slide. There is no trace of any felspar or quartz. (See 

 plate II, fig. 8.) 



Nos, -gf-g to gf-^ are somewhat doubtful rocks. ^| ¥ is a serpentin- 

 ised rock of some sort with colourless hornblende (tremolite) 

 visible in it, much cut up, and invaded by the serpentine. The other 

 two rocks are complete puzzles to me. They possess large plates of 

 some mineral, broken up into small disconnected patches extinguish- 

 ing light together, and between the separated ragged grains of which 

 there is a clear colourless mineral running as veins through the 

 rock. Mr. Holland suggests the former to be augite, from the 

 * lattice' structure visible, and the latter serpentine. 



No. ¥ fg- is a plagioclase rock with micro-crystalline ground-mass, 

 and porphyritic crystals of felspar and quartz present in it. The 

 rock is much changed and bleached. It contains yellow epidote in 

 irregular granules especially surrounding the porphyritic quartz 

 grains. 



No. -gf 7 was probably originally a diorite. It contains triclinic 

 felspar, chalcedony in buff-coloured patches, green hornblende which 

 in places seems to have become bleached to a colourless hornblende, 

 remaining at the same time in optical continuity with the coloured 

 part, green epidote in grains and micro-crystalline aggregates 

 apparently derived from the decomposed felspar, and sphene. 



Petrologzcal Summary* 



In the preceding pages we have found distinct evidence for — 



(i) A metamorphic series, that is to say, a set of sedimentary 



rocks that have been variously metamorphosed ; in 



some places only slightly so, and but thinly disguising 



their clastic origin and obvious position among the 



( 84 > 



