8 WALKER : GEOLOGY OF KALAHANDl STATE. 



hornblende, biotite and quartz are usually present in varying amounts. 

 It will thus be seen that the rocks in question differ somewhat 

 from the typical charnockites described by Mr. Holland, 1 though I 

 incline to the opinion that they all belong to the same petrological 

 province. The ^granitoid gneiss described in the last chapter is also 

 characterised by the presence of small quantities of the pyroxene seen 

 in the Kalahandi charnockites. (Specimens 15* 178 and 15- 179.) 



V.-THE GARNET SILLIMANITE SCHISTS- 

 KHONDALITE. 



Most of the hills rising from the 800-foot and 3,ooo-foot plateaux 

 as well as those along the Ganjam-Kalahandi frontier are composed of 

 rocks, usually foliated, consisting of quartz, garnet, sillimanite and 

 graphite. In hand specimens they are greyish to reddish in color and 

 frequently shew numerous small shattered red garnets in a very much 

 crushed groundmass. The microscope shews that the groundmass is 

 made up of quartz grains penetrated by innumerable disjointed sillima- 

 nite needles usually more or less parallel, and occasional ragged flakes 

 of graphite, see PI. 2. The sillimanite is sometimes made up of almost 

 hair-like needles, so that the quartz sillimanite intergrowth approaches 

 typical fibrolite, at other times, it forms independent disjointed 

 crystals of considerable dimensions. The specific gravity varies from 

 2*85 in the more quartzose varieties to about 3*05 in the more 

 garnetiferous. (Specimens i5i"8o, 15* 1 81 , 151 87 .) 



These rocks are well defined schists, apparently altered sediments 

 overlying the granitoid gneiss, charnockites, and in some instances 

 the more massive gneisses of the crystalline complex. Along the 

 Ganjam frontier the hills are almost entirely made up of sillimanite 

 garnet schists. Farther south in the 3,000-foot plateau it is usual to 

 find charnockite or granitoid gneiss exposed in the valleys and on the 

 lower slopes of the hills, the main mass of which is composed of sillima- 



1 Mem. Gcol. Surv. Ind„ Vol. XXVIII, p. 119. 



