SUMMARY. 213 



V.~ SUMMARY. 



Elaeolite-syenite forms the main mass of the large hill of Siva- 



malai (n°3' ; 77°36') i n the Coimbatore district, 



Loc ^S>SS^^£ thC as well as of the row of six or seven small 



hillocks stretching away in the west-north- 

 west direction. The rocks present a well-marked foliation, 

 generally in conformity to that of the gneisses around, in which 

 their outcrops present the appearance of lenticular masses. The 

 foliated structures, however, must have been impressed before 

 complete consolidation, as the rocks show no signs of subsequent 

 crushing. 



The elaeolite-syenites are accompanied by augite-syenites con- 

 taining olivine, agreeing in this feature with the 



Augite-syenite. 



laurvikite described by Broggerfrom the famous 

 Christiania district of Norway. The other constituents of the augite- 

 syenites are, in approximate order of abundance, microperthitic fel- 

 spar, green non-pleochroic augite, opaque black iron-ores, zircon, 

 hornblende, hypersthene, apatite and biotite. 



These rocks are accompanied by others made up principally of 



felspar (albite and orthoclase), containing 



Corundum -syenite. . . _ 



large quantities of well crystallized, generally 

 tabular, corundum, which is extracted by the villagers near the 

 junction of the felspar- rock with the elaeolite -syenite. As accessories 

 in this rock we find chrysoberyl, garnet (near rhodolite), blue 

 apatite, magnetite, zircon, muscovite, biotite, and automolite. 



The association in this area is remarkably similar to that of 

 Eastern Ontario described by Adams, Barlow, Coleman and Miller, 

 and to that of the Urals described by Morozewicz. 



Chief types of ekeolite- The elaeolite-syenite presents five well-marked 

 s * emte - forms at Sivamalai. 



[a) An even-grained, foliated, grey variety, which is the prevalent 

 form and contains graphite, biotite and magnetite as the 



( 45 ) 



