20. NOTES ON COMMON OPAL DEPOSITS IN EAST 
GIPPSLAND. 
(.Extracted from Report by W. II. Ferguson .) 
Common or milky opal occurs in a number of places in the Gelantipy 
district, the largest deposit being situated at “ W. Tree,” on the Gelantipy 
to Buchan road, where a shaft and an excavation, both partly fallen in, 
disclose opal between 1 and 2 feet thick ; the mode of occurrence cannot, 
however, be clearly seen. The rocks of the neighbourhood are porphyry, of 
the Snowy River fragmental series, and basalt, which rests on the porphyry, 
and in which the opal apparently occurs. 
Portion of the basalt is very vesicular, and the vesicles are in places filled, 
with zeolites, and chalcedony of a white and light-blue tint. Some of the 
amygdaloidal basalt has a fine appearance, and would doubtless take a 
handsome polish. 
From Buchan to Deddick, along the Snowy River valley, there is abund¬ 
ant evidence of the deposition of minerals from solution. The porphyry 
in various places contains veins of barium sulphate, jasper, quartz and 
calcite, and deposits of agate. 
If the deposit at “ W. Tree ” were properly opened up, blocks 2 feet in 
diameter could be obtained. On the surface, the stone is much flawed and 
jointed ; in depth, solid stone could probably be obtained. The colour ranges 
from milky-white, yellow, brown, and red to black, and is beautifully 
streaked and mottled. Some of the stone decomposes freely at the surface. 
No precious opal was noticed in the deposit ; it is locally reported that such 
has been obtained. In places, a superficial iridescent decomposition tarnish 
may be seen, but no deep-seated play of colours. The stone is apparently 
susceptible of a very high polish, and could possibly be used in the manufac¬ 
ture of clock-stands and other useful and ornamental articles. A few ex¬ 
cavations would prove the extent of the deposit, and enable samples to be 
obtained with the view of ascertaining whether it is likely to be of commercial 
value. 
Similar opal is reported to exist at Fan wick and other localities eastward 
from “ W. Tree,” and to be associated with basalt and granite. 
Common opal occurs in the Western District of Victoria, near Mount 
Stavelev and the township of Wickliffe, where it occurs in porphyry, and in 
Ordovician strata in contact with porphyry. 
Kilcunda, 20th February, 1900. 
PRESENT® 
12m 1904 
By Authority : Robt. S. Brain, Government Printer, Melbourne. 
