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 Ta 
Sesqui-oxide of chromium 
Alumina .. 6 
Magnesia ... ax, 
Water au oo 
nee coe 47515 
tee eee 761 
see .. 3323 
see oe 456 
tee 6:23 
98°78 
Which gives as oxygen ratios of proto- and per-oxide bases and silica 1:9:12 
corresponding to the formula— 
MgO SiO, +3 (8/9 Al,0,+ 1/9 Cr,0,) SiO, +3 HO; 
(1/10 MgO, + 9/10 (8/9 A1,0, -+ 1/9 Cr.0,)} SiO, 6/5 + 1/3 HO. 
16. BiotrrE (Hexagonal Mica). 
Fiddler’s Reef, Forest Creek. 
4 sheet 14 S.E. 
Occurs in a decomposed basaltic dyke. 
17. Muscovıte (Oblique or Com- 
mon Mica). Map No. M, 25. 
Hell’s Corner, Baynton, 4 sheet 
51 S.W. 
Occurs in nests in the granite, along 
its junction with the Lower Silurian 
sandstone, associated with tourmaline. 
18. HORNBLENDE. 
Anakie Hills. + sheet 19 N.E. 
Occurs in crystals and crystalline 
pieces, with splendent cleavage planes, 
in scoriaceous basalt, associated with 
oligoclase. An analysis, by Mr. R. 
Daintree, late of the Geological Survey, 
afforded :— 

Silica ti 41'367 
Sesqui-oxide of iron 20'350 
Alumina see +e» 20900 
Lime ees 8'181 
Magnesia 6:834 
97°632 

19. HoRNBLENDE. 
Fiddler’s Reef, Forest Creek. 
; sheet 14 S.E. 
20. Brown TOURMALINE. 
Marysville Company, Dalhousie. 
Occurs with iron pyrites in quartz, 
associated with micaceous sandstone, 
21. Ossian (Buttons). 
Plain near Mount Talbot Home 
Station, Wimmera District, 
Specific gravity, 2°47. 
Presented by Suetonius Officer, Esq. 
22. OBSDIAN BALL. 
Upper Regions Station, Horsham. 
Specific gravity before the specimen 
was cut, 1°06. 
Presented by Thomas Edols, Esq., 
through Messrs. Francis and 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 
