Baih/iiuj Stones of Victoria. 191 



fifteen years, showed that there was little or no difference, ^r^ 

 that the stone appears to have good weathering properties, 

 (See Plate XL, Fig. 2.) 



Bacchus Marsh Stone. 



It was a matter of some difficulty to obtain a thin section 

 of this stone for microscopical examination, owing to its weak 

 binding properties. The stone is made up of fine grains of 

 angular quartz set in a fine-grained matrix of argillaceous 

 material stained brown by ferric oxide. Occasional crystals of 

 mica and felspar occur through the section, but the stone is 

 almost entirely made up of sand grains, and a fine-grained 

 matrix. The proportion of grains to matrix is far too small to 

 allow of a good weathering stone, as the cementing matrix is of 

 an argillaceous character, and so a poor binding material ; thus 

 from microscopical evidence one Avould conclude the stone to 

 have a low crushing strength, and to have very little weather- 

 resisting properties. (See Plate III., Fig. 1.) 



Barley Stone. 



This stone resembles closely that from Bacchus Marsh, but 

 contains more fine-grained matrix, and in addition carbonates 

 are present. Tlie grains of quartz are small and angular, and 

 well separated from one another. From the amount and argil- 

 laceous nature of the matrix, together with the presence of 

 carbonates, one would consider the stone to have poor weather- 

 ing properties, and to have a low crushing strength. (See Plate 

 ni.. Fig. 2.) 



Egerton Stone. 



Fine-grained. — This is made up of very fine grains of quartz, 

 set in a matrix of argillaceous material. The quartz grains are 

 subangular, and of fairly even size. There is a fair percentage 

 of fine-grained matrix, which is evenly distributed, and does not 

 occur in large isolated patches. This stone is much superior 

 to the Bacchus Marsh and Darley stones, from a microscopical 

 point of view, and indicates good weathering properties, along 

 with a fairly high crushing strength. (See Plate IV., Fig. 1.) 



