48 



HENRY G. SMITH. 



hood of Sydney, induced me to make this investigation. The 

 exact locality from which these garnets were taken, is about half 

 way between Miller Street and the Glebe Island Bridge, on the 

 right hand side. A small amount of work has been done there, 

 but has apparently been stopped. 



The conglomerate consists of a thin layer covering the bed of 

 sandstone, which is nearly horizontal, having but a slight dip 

 towards the north. The garnets are very minute, and do not 

 consist of perfect crystals, being principally fragments ; in fact, I 

 could only detect traces of faces on one or two of them. The 

 colour is light in most instances, although some are deep red, and 

 others inclining to purple, having all the characteristics of stones 

 of this group known as " precious garnets." The lustre is good, 

 and there are little signs of decomposition. 



It was found advisable to crush the conglomerate and wash it 

 to obtain the garnets, which can be readily picked out of this 

 material when dried, better with the aid of a lens; the remaining 

 portion being largely composed of water worn quartz pebbles, 

 some mica, and a few jasperoid stones mostly of a green colour. 

 The reason these garnets are in fragments is apparent when 

 placed under the microscope, the cleavage being beautifully marked 

 and quite distinct; in some instances the apparent cubical cleavage 

 is so striking, that the resemblance to that of galena is at once 

 suggested. 



The conglomerate from which these garnets were obtained was 

 most probably derived from the decomposition of granite, as the 

 gravel has all the appearance of coming from that source, and 

 there can be little doubt but that the garnets were derived from 

 this granite also. A specimen from Albury, New South Wales, 

 is before you, of a granite containing garnets, very much resembl- 

 ing those obtained in Sydney, being almandine garnets, small, 

 and of much the same colour. 



It is not probable that these garnets were obtained from the 

 basaltic rocks common in the Hawkesbury deposit, because when 

 heated before the blowpipe they readily fuse, become quite black 



