A RAVALLI SYSTEM. 30 



rich in potash felspar, quartz and biotite, and obviously must be 

 classified with the granite aplites. Of these, No. £& (12315), 

 intrusive in the calc-gneiss of the low hills S.S.E. of Khed Brahma, 

 has the usual white or grey colour, medium grain, and the scales, 

 of biotite arranged in streaky lines, and also in eyes or nests, 

 following the direction of the veins. These nests, or glomero-porphy- 

 ritic groups, are frequently associated with a reddish-orange garnet, 

 (PI. 10, fig. 1). The most prominent mineral is microcline, occurring 

 in numerous, rather small, roughly euhedral shapes, the almost 

 square basal sections showing the characteristic coarse " grating " 

 structure and giving extinction angles of about 15°. See (12315) 

 second slide, PL 10, fig. 2. There are also many rather 

 large porphyritic crystals, also of microcline, with roughly ldio- 

 morphic, but not very sharp, outline. Soda-lime plagioclase is 

 practically absent from this rock. Quartz is in large and small 

 grains and interlocking areas, fairly full of minute fluid inclusions. 

 Micropegmatite, in small curved or elliptical areas, wanders about 

 the microcline like a disease (in one slide). The biotite, giving 

 pale greenish-yellow and dark brown pleochroism, occurs as scattered 

 plates of moderate size, which are aggregated into nests and streaks. 

 It is associated with and often surrounds a garnet grain, the mica 

 plates being arranged parallel to the edge of the garnet. Apatite 

 occasionally appears as an accessory, and there is practically no 

 iron ore. There is a little dark-blue tourmaline (indicolite). 



Another specimen which I select for description, as being of a 

 different type, is from the hills \ mile east of Damavas, No. ffc 

 (12316), and is intrusive in the biotite-gneiss. It is of rather an 

 exceptionally fine grain, darker grey colour, and differs from the 

 majority of the veins in the same neighbourhood which are of the 

 ordinary aplite type. Perhaps the specimen is more of a fine- 

 grained granite than an aplite. Besides biotite, there is a fair 

 amount of silvery-white mica and some zircon. The potash felspar, 

 though generally showing the repeated twinning of microcline, 

 appears also to include some orthoclase. There is also a little 

 plagioclase giving extinction angles of 16° to 20°, and which there- 

 fore is probably andesine. There is much quartz with abundant 

 minute fluid cavities and some red-brown garnet here and there. 

 No iron ores. 



The specimen from Asai hill, S.W. of Vadali No. 4 \^ 6 (12317), 

 is a very typical example of the granite -aplite of these parts, both 



