OCCURRENCE OF A NEW MINERAL AT BROKEN HILL. 367 
These analyses correspond almost exactly with the formula 
CoS,, NiS,, CoSb,, NiSb,, or a sulph-antimonide of nickel and 
cobalt. When first discovered the mineral was supposed to be a 
sulph-antimonide of cobalt, but Mr. Mingaye’s analysis shows it 
to contain equal quantities of cobalt and nickel, although it is of 
course just possible that future discoveries may show that these 
two metals may replace one another in varying proportions. The 
mineral which agrees most closely with willyamite is ulmannite, 
a sulph-antimonide of nickel NiS,, NiSb,. In the last edition 
of Dana’s ‘System of Mineralogy,” several analyses of ulmannite 
are quoted which show that mineral to contain a trace of cobalt, 
and one specimen is quoted as containing 1:06 per cent. of cobalt 
in connection with twenty-six per cent. of nickel. The presence 
of equal quantities however of cobalt and nickel in willyamite 
appears to justify its recognition as a new mineral. Mr. Smith 
informs me that a small quantity of the new mineral only was 
found associated with a lump of dyscrasite in a gangue of calcite 
and siderite at a depth of one hundred and fifty feet (vertical). 
I have tested the physical and pyrognostic characters of the 
mineral, and they are as follow :—System of crystallisation, 
isometric. Cleavage, cubic, perfect. Fracture uneven, brittle. 
Hardness, about 5:5. Specific gravity (mean of a number of | 
experiments) 6°87. Lustre metallic. Colour between tin-white 
and steel-grey. Streak greyish-black. In the closed tube and 
next to the assay yields a dark red sublimate, which is orange 
coloured on cooling, and this is surmounted by a faint white 
sublimate. In the open tube decrepitates, yields antimonial and 
sulphurous fumes; near the assay the white sublimate shows in 
fern-like forms. Before the blowpipe on charcoal, fuses readily to 
a globule, which boils and emits sulphurous and antimonial fumes. 
With borax glass gives at first the cobalt blue colour, but after 
oxidising all the cobalt, the nickel reaction is subsequently obtained. 
Decomposed by nitric acid with separation of antimony trioxide. 
The Australian Broken Hill Consols Lode in which this mineral 
was found, differs materially from the other lodes on the field, 
