Physiography of Bulla Area. 



2 "S 



a 



•■35 2=5 2 5^ :=H ;c'5 



SiO^ - 08.92 - 71.65 - 70-91 -66.13 - 71.57 - 69.19 - 67.75 



AI2O3 - 15.26 - 14.56 - 13.99 - 16-83 - 13.58 - 13.45 - 16.11 



Fe^Og - .80 - 1.13 - .35 - 1.11 - I.I8 - 2.71 



FeO .- 3.30 - ].56 - ' 3.02 - 4.17 - 2.19 - 2.78 



.50 

 4.00-' 

 MgO - 1.64 - .81. - .80 - 1.83 - 1.07 - 1.06 - .79 



CaO - 3.04 - 1.27 - 2.35 - 3.2J - 1.72 - 2.04 



Na.,0 - 2.71 - 2.76 - 3.94 - 2 25 - 2.79 - 2.89 



2.68 

 2.60 



K.,0 - 2.93 - 4.14 - 3.66 - 3.14 - 4.36 - 3 94 - 3.42 



H,0 + iio 1.04 - .15 - .21 - 1.68 - .69 - .77 - .96 

 H^O - 110 .22 - 1.20 - .11 - .23 - .11 - .16 - .20 



CO.2 - Nil - Nil - Nil - Tr. - .29 - .07 - Nil 



TiO^ - .70 - .35 - .58 - Tr. - .46 - .51 - .85 



P2O5 . .19 - .12 - Tr. - Tr. - .11 - .18 - .09 



MnO - Tr. - .(J4 - Nil - .07 - .09 - .14 - Tr 



Li^O - 'J'r. - Tr. - — - _ Tr. '^'r. — 



CI 



Nil - 



Tr. - 



— 



.- Tr. - 



Tr. - 



Tr. - 



— 



Total - 



100.75 - 



99.77 - 



99.95 



100.70 - 



100.21 - 



99.89 - 



99.95 



S.G. 



2.688 - 



2.630 - 



— 



2.677 - 



2.655 - 



2.666 - 



2.68 



Q g- i2 ^ K 53 



I < I S d d 



The rather high CaO content, and the relatively low K-^O content 

 of the Bulla rock favours granodiorite rather than adamellite, and 

 the miscroscopical examination confirms this determination. 



Megascopic Character . — It is a rather coarse grained, grey rock 

 with many crystals, 10 mm. in diameter. Quartz, plagioclase, 

 orthoclase, biotite and a little pyrite can be seen. The quartz has 

 a greasy lustre, and the felspar tends to be greenish. The rock 

 takes a fine polish, though the coarse biotite is inclined to give the- 

 surface a chipped appearance. Basic segregations with their 

 rounded outlines are very common. Ihe specific gravity of fresh 

 rock is 2.677, and thus in keeping with its determination as 

 granodiorite. 



Microscopic Character. — It is a non-porphyritic, hypidiomor- 

 phic, holocrystalline rock with crystals of various 'sizes. It is 

 medium to coarse in grain, with a rich assortment of minerals.. 



