IDAR GRANITE, GRAXOPHYRE, ETC. 12 5 



Wantra hill, is a purplish-grey rock with much very beautiful micropeg- 

 matite, the felspar being microcline and orthoclase with Carlsbad 

 twins ; 4 2 50 , from Ora, is a dull purple micro-granite with abundant 

 quartz, microcline and orthoclase and with micropegmatite. Biotite 

 is scarce. 



A moderate proportion of the granite of Tdar State has green 

 With hornblende. hornblende in addition to biotite, and the 



quantity is sometimes large. In the rock at 

 the foot of the temple hill S.E. of Dhabal, ffa (12178), a finely 

 porphyritic handsome rock, the hornblende (basal sections' of which 

 give Hooker's green and greenish yellow pleochroism) is not very 

 largely developed. Jft, at Dungri near Bhadresar, contains a 

 fair amount, and also ffa from Viravada, the pleochroism of 

 which is very noticeable in greenish yellow (X). bright green (Y), 

 and greenish blue (Z) tints, suggestive of pargasite. There is (?) 

 a little sphene or leucoxene surrounding the iron ore in the biotite 

 The Kawarock, 5 2 ^ (12170. PI. 11, fig. 5)j a ] roadv mooned, and of 

 which a chemical analysis has been quoted, is also a handsome rock 

 porphyritic with dull pink crystals of microcline. and mottled 

 grey and black ground-mass. It contains much microcline and 

 quartz, also plagioclase (albite-oligoclase). green-yellow hornblende 

 and biotite. the two latter grown together in' clusters. Other 

 similar rocks, such as the very coarse Mohr rock. ^ (12472), 

 belong to this categorv. 441 



On the eastern face of Dharol hill there is a variety of the granite 

 Witli (?) topaz. 5 l <>! ( 12l8 °)- PI- 1 '• fig. 6 <>f pale pink colour and 



medium grain, containing bleached biotite of the 

 palest drab colours, very much plagioclase (albite-oligoclase) much 

 microcline and some quartz crowded with inclusions. It also contains a 

 few rather small plates of a brilliant white colour, with rather high 

 refractive index and weak double refraction, they are biaxial and 

 positive. In another rock, *[\ the same mineral shows a good 

 basal cleavage giving straight extinctions. I have referred this mineral 

 tentatively to topaz. At the valley head, j mile south of Nadri 

 s 2 ^ occurs, resembling 5 2 /> so exactly that they are probably a 

 single band in the granite. 



On both the western and eastern edges of this same hill, 

 Withi.ini.e. apparently near the edge of the Idar granite! 



occur masses and veins of the granite con- 

 taining bright yellow pinite as the sole dark mineral. 1 Sometimes 



K 



