VICTORIAN MINERALS.—CASE XIV. . 79 
15. SELWYNITE. List No. R 120. 
West of Mount Ida, near Heathcote. 
= Occurs as a vein in the Upper Silurian rocks, traversed by thin 
seams of talc, and accompanied by a white magnesian mineral and two 
other undetermined minerals. According to Mr. Ulrich, it is allied to 
pyrosclerite, but differs materially from it in its chemical composition and 
physical properties, and therefore forms a new mineral species, which is 
named after Mr. Alfred R. C. Selwyn, the Director of the Geological 
Survey of Victoria. A quantitative analysis, by Mr. J. Cosmo Newbery 
afforded the following results :— :: 
Silica y wae u aoe +. vee 4715 
Sesqui-oxide of chromium ... z ar cp AGEL 
Alumina ... ote ate 5 4i -asy CEWE) 
Magnesia ... se tee see an .. £56 
Water... = So To; m ao (PRY 
i 98:78 
-— 
Which gives as oxygen ratios of proto- and per-oxide bases and silica 1:9:12 
corresponding to the formula— ; ; 
MgO SiO, +8 (8/9 Al,0,+ 1/9 Cr,0,) SiO, +3 HO; 
; iy $ 
(1/10 MgO, + 9/10 (8/9 Al,0, + 1/9 Cr,05)} SiO, 6/5 + 1/3 HO. 
16. Biorrrr (Hexagonal Mica). 19, HORNBLENDE. 
Fiddler’s Reef, Forest Creek. Fiddler’s Reef, Forest Creek 
3 sheet 14 S.E. 7 
Occurs in a decomposed basaltic dyke. i sheet 14 S.E. 
17. Muscovire (Oblique or Com- | 99 Brown TOURMALINE. | 
mon Mica). Map No. M. 25. ý 
Hells Corner, Baynton. $ sheet Marysville Company, Dalhousie. 
51 S.W. Occurs with iron pyrites in quartz, 
Occurs in nests in the granite, along | associated with micaceous sandstone, — - 
its junction with the Lower Silurian : i 
sandstone, associated with tourmaline. 
21. OssīpIaN (Buttons). 

18. HORNBLENDE. 
Anakie Hills. + sheet 19 N.E. Plain near Mount Talbot Home 
Occurs in crystals and crystalline Station, Wimmera District, 
pieces, with splendent cleavage planes, Specific gravity, 2'47. 
in scoriaceous basalt, associated with 
oligoclase. An analysis, by Mr. R. 
Presented by Suetonius Officer, ESN 
Daintree, late of the Geological Survey, 
' afforded :— ' 
Silica’ se a ° « arse | 22- OBstDrAN Barr, 
Sesqui-oxide of iro “4. 20°350 Upper Regions Station, Horsham. 
Alaming E aL rater Specific gravity before the specimen 
ame woe eee eee was cut, 1:06. 
Magnesia ase oe = 6834 
Presented by Thomas Edols, Esq., 
97°632 | through Messrs. Francisand McPherson. 


Note.—Button-shaped, spheroidal pieces of obsidian are found 
abundantly scattered over the basaltic plains of Mounts Elephant, Eeles, 
&c., and the mud-plains of the Wimmera district, the latter far removed 
from any known craters or points of eruption. Specimen No. 22 is a 
