TANTALUM AXD XIOBTUM IX W. AUSTRALIA. 313 



consist (except for three fragments) of euxenite in ang-ular pieces fi'om 

 half a gramme up to fifty-seven grammes in weiglit. Several showed 

 indistinct traces of crystal faces. Associated with the euxenite was one 

 piece of cassiterite and two of gadolinite. The locality of this 

 specimen is undoubtedly Cooglegong, and it is alluvial in origin. The 

 surface of the mineral is dull and brown in colour from decomposition. 

 On a fresh fracture it has a brilliant resinous lustre, and is-olive brown 

 in colour. On wetting, the colour is seen to be somewliat mottled, 

 varying from liglit to dark olive brown. In mass it is opaque, but in 

 a powder under the microscope it is transparent, light brown and, like 

 the fergusonite, isotropic. Its hardness is 7 and specific gravity 5"1 to 

 5-4. The central portion of a fragment weighing about twelve 

 grammes was taken for analysis. 



E uteiiitc, Cooyleyon (/ . 



Tantalum pentoxide 23-10 per cent. 



Niol)iinn pentoxide 

 Titanium dioxide 

 Tin dioxide 



Thoria 



Yttria 



Erbia 



Ceria 



Lanthana and didymia . . . 



Lime 



Iron protoxide 



Manganese protoxide 



Magnesia 



Uranium trioxide 



Alumina 



Iffnition loss 



Sp. gr. 5 '3 7. 1 



A sample of alluvial tin ore from Cooglegong in the Geological 

 Suiiroy collection (No. 2026) was examined by Prof. Stanley's metliod. 

 30 grammes yielded 28-3 grammes of cassiterite and a residue of 

 thirty-one small fragments, thi-ee of which were quartz, three magne- 

 tite, and one monazite. The remaining twenty-foui- appeared to in- 

 clude both euxenite and fergusonite. 



A parcel of alluvial monazite concentrates from Cooglegong cdu- 

 tained small lunportions of cassiterite, euxenite, columbite, and 

 probably fergusonite. 



Anotlier sample of alluvial tin ore from the Shaw Tintield, near 

 Cooglegong, was also examined. It was somewhat fine grained, 70% 

 passing a 10-mesh sieve. Twenty-five graimnes of the coarser particles 

 were tested and yielded 93% cassiterite. Most of the balance was 

 rnonazite, but a few small crystals of tantalite were present. 



WoDiiixA. — In my previous paper mention was nuide of the occm- 

 rence of microlite in this district, and as this mineral had not jti-e- 



