On tlie Occurrence of the Diamond near Mudgee. 101 



pounds weiglit of tMs mineral are obtained from each cart-load 

 of gravel washed. 



2. Topaz occurs in water-worn fragments, and sometimes in 

 crystals ; transparent, and commonly white ; rarely yellow or 

 very light blue. The Topaz is the largest of the accompanying 

 minerals, varying in size up to half-au-inch diameter. 



3. Qtiao'tz. — Opaque double hexagonal pyramids, one-eighth to 

 one-fifth inch diameter, are very common. Quartz pebbles occur 

 of all sizes. The varieties comprise agate of poor quality, 

 cornelian, jasper, rock crystal, smoky quartz, and a kind which 

 appears bluish opaline when wet. Pebbles of grey quartz, 

 imbedding felspar, derived from a granite very similar to that 

 which occurs at Aaron's Pass, fifty miles higher up the river. 



4. Corundum. — 



(a.) Sapphire, transparent, blue, green, yellowish, or parti- 

 coloured. 



(5.) Adamantine spar, hair brown and black. 



(c.) The opaque magenta-coloured variety of alumina, which has 

 received the name of Barklyite in Victoria. 



All these occur in small fragments in great abundance. 



(d.) Another variety, which is characteristic of this locality, has 

 to be mentioned. It is in six-sided prisms, slightly barrel- 

 shaped or tapering, with flat end faces ; i inch long, not 

 exceeding l-20th inch diameter ; bluish-white, with a few 

 dark-blue spots ; opaque ; hardness, 9 ; specific gravity, 

 3"59 ; composition found by analysis — 



Alumina 98-57 



"Ferric oxide 2*25 



Lime '45 



101-27 



(e.) Muly. — A transparent pink variety of corundum ; is found 

 sparingly in flat grains up to 1-lOth inch ; its shade often passes 

 into violet and blue ; hardness, 9 ; specific gravity, 3-96 ; compo- 

 sition found by analysis — 



Alumina 97-90 



Ferric oxide 1-39 



Magnesia -63 



Lime "52 



100-44 



(/) A few large rolled pebbles of corundum have also been 

 observed, exceeding \ inch, of a mottled dirty white and pink 

 colour, perfectly opaque. From their low and variable specific 

 gravity, 3-21, 3-44, and upwards, they appear to be impure massive 

 forms of the mineral ; they possess the requisite hardness. 



