Rocks near Heathcote. 347 



felspars and actinolite (?) Irregular altered augite crystals lie in a 

 tine-textured silicitied ground-mass. 



2. Rock Section 612 x 11 diameters. 



Bedded chert, section on radway, 30 yds. S. of Gate 47, Heath- 

 cote Some of the dark patches are of igneous material. The 

 circular colourless areas with inner walls (?) are probably organic. 

 The I'ock has been intensely silicitied. 



i. Rock Section 549 x 11 diametei-s. 



Jasperoid alteration of diabase, 300 yds. S. of selwynite out- 

 crop and W. of Murray Road, Heathcote. The igneous texture 

 of the rock lias been completely lost by secondary silicitication. 

 lladial chalcedonic aggregates form the bulk of the I'ock and are 

 traversed by later quartz veins. 



4. Rock Section 592 x 1 1 diameters. 



Calcareo-siliceous alteration of diabase or diabase tufF, 200 yds. 

 N.W. of S. Heathcote Hotel, and E. of Murray Road. Calcai'eous 

 areas represent the earlier alteration of the rock. Later siliciti- 

 cation has ol)literated much calcareous material, the boundaries 

 of areas formerly calcareous being defined by dark lines in the 

 present chalcedonic ground-mass. 



Plate XVI. 



1. Rock Section 550 x 11 diameters. 



Boulder of corundum and green micaceous mineral from Gully 

 just E. of jasperoid and 300 yds. S. of selwynite outcrop. Heath, 

 cote. Coi'undum occurs in elongated prisms and also in irregular 

 masses at the right-hand side of the photograph. Orthorhombic 

 pyroxene (?) occurs in broad prisms on the left-hand side, and the 

 light l)ackground consists of a pale green micaceous mineral. 



2. Rock Section 551 x IS diameters. 



Silicitied diabase with corundum, a few feet from jasperoid and 

 300 yds. S. of Selwynite outcrop, Heathcote. The long prisms 

 formerly corundum, are now replaced by secondary minerals. The 

 igneous texture of the rock is partially obscured by radial 

 crystallization of chalcedonic silica. 



3. Rock Section 56G x 11 diameters. 



Selwynite from outcrop junction of .Murray Road and road 

 running N.W. towards Derrinal ; about 2^, miles N. of Heathcote 



