142 
The South Australian Naturalist. 
the crystal being attached to the rock by the middle of the prism. . 
“Cairngorm, ”used as ornaments, was a form of highly polished 
quartz. Twelve-sided garnets from the Mai jy States were shown, 
and their perfect symmetry was pointed out and admired. Crys- 
tals exhibited different habits or dispositions. Mica consisted of 
perfect crystals laid flat upon one another in laminae or plates. 
Asbestos, on the other hand, was composed of long narrow fibres, 
from which fireproof curtains and a silky kind of fabric could be 
woven. Galena (sulphide of lead) was arranged in perfect cubes, 
and when broken separated into tiny forms of a like structure. A 
topaz of pigeon-blue color found at the Hoffnung mine, Victoria, 
had been the subject of protracted litigation. Coorongite, from 
the Coorong, was a substance of leathery appearance which burned 
readily, and was once believed by the “man in the street” to indi- 
cate the presence of oil. Pelionite, from Alount Pelion, lasmania, 
was a true oil shale. Although it did not burn readily, h gave out 
the characteristic bituminous odor. ITbes of “fulgurite” (light- v 
ning stone) were explained as caused by electric discharges into j 
the sands of the shore. Specimens of obsidian or “blackfellows^ [ 
buttons,” picked up by Mr. E. tf. Ising on the Nullabor Plains, 
were supposed to be due to a meteoric shower which had swept the ' 
southern half of the Australian continent. These were sold to the 
whites by the aboriginals. Gold was not the most valuable of^ 
metals. Osmiridium (composed of the two metals osmium and j 
iridium, and found in Tasmania) had a much higher commercial 
value. It was used for the hard tips of fountain pens. Radium, 
also, which had been discovered at Olary, on the Broken Hill rail- 
way line, was practically priceless. The phenomenon of the twin- 
ning of crystals was explained. The junction of two crystals in 
gypsum produced a peculiar arrow-headed crystal. A fossil 
shark's tooth, embedded in nummulite (coin shaped) limestone 
fossils and hot lava from Vesuvius, afforded further examples of 
crystallisation. The lucid explanations of Dr. Fenner was sup- 
plemented by illustrations on the blackboard, and samples of all 
the minerals discussed were handed round. 
LECTURE, “GIPPSLAND RANGES AND LAKES,” BY 
MR. H. HORSWILL, JUNE 17, 1924.— Professor J. B. Cleland 
presided. The lecture was illustrated by a large number of lan- 
tern slides of exceptional merit from photographs taken by the lec- 
turer. A descriptive account was given of the trip from Mel- 
bourne to the lakes entrance and back. The grandeur of the 
mountain scenery was depicted and the magnificent forest cover- ^ 
ing of VIount Baw Baw and other places en route was shown onj 
the screen. This district grows the largest trees in the world, j 
Authentic records give the highest trees as 375 ft., which is the 
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