TAXTALU.M AXD XIOBIUM IX W. AUSTRALIA. 311 



These '' residues ' were somewhat coarse grained, the particles averag- 

 ing about 3inm. in diameter- and only 0'2% passing a 10-mesh screen. 

 A separation effected on the lines described above showed its com- 

 position to be' — 



Cassiterite ... ... 26'3 per cent. 



Monazite 26'2 



Garnet TO „ 



Columbite ... ... 46-5 



lOO'O per cent. 



TJie chief base present in the columbite is manganese. The average 

 specific gravity is 6-1, indicating the presence of about 40% of 

 tantalic oxide and 43% of niobic oxide. The mineral is opaque and 

 Talack in colour, and rather dull on the surface. The majority of the 

 fragments are quite irregular in outline, but a large number are in 

 flattened pieces, in which the faces XX, a, and a^ are well developed. 

 Faces b, c, and possibly u are imperfectly seen. 



Columbite having been found in such profusion in this material, 

 a search was made for it in thi-ee one-hundredweight parcels of stream 

 tin concentrates from the Moolyella district. The first was from 

 Moolyella proper, the second from Tadgebanna, the third from Mud 

 Springs. The following results were obtained : — 



Size — Refused 20 mesh 

 Passed 20 mesh 

 Metallic tin by wet assay . . . 

 Tantalic and niobic oxides 

 Equal to columbite 



Some of the carefully separated columbite was found to be identical in 

 appearance with that obtained from the "Sluice-box Residues'". One 

 unusually large fragment had a specific gravity of 5-80 corresponding 

 to a mangano-columbite with 26% of tantalic oxide and 56% of niobic 

 oxide. Associated with the cassiterite and columbite wera small pro- 

 portions of an almost colourless garnet, monazite, magnetite, quartz, 

 ^nd in one case albite. 



CooGLEGOXG. — -This continues to maintain its reputation as a 

 mineral field of exceptional interest. In my previous paper reference 

 was made to the occunrence at this spot of euxenite, monazite, and 

 gadolinite. I have now to record further the occurrence of fergusonite 

 for the first time in Australia. A parcel of alluvial material recently 

 forwarded to me from Coogiegong, and described as coming from a 

 gully on the sides of Trig Hill, was found to consist wholly of this 

 mineral in a more or less weathered state. Individual fragments 

 varied from about h gramme up to 6 or 7 grammes in weight. They 

 were mostly angular pieces devoid of ciystalline form, but some were 

 somewhat fan-shaped imperfect crystal aggregates. Exteiiially the 

 pebbles were mostly dull and covered with a brownish red or grey 

 adherent coating, consisting of decomposition products. On a fresh 

 fracture the minei-al is brownish black and brilliantly vitreous. It is 

 opaque except in very thin splinters under the microscope, when it is 

 transparent, colourless or very pale greenish brown in colour, and 



