xvn 



OBSIDIAN BUTTONS. 



The Chairman (Mr. T. Stephens) produced some farther notes on 

 •■ Obsidian Buttons." 



Since my paper was read at the September meeting, I have received 

 from Sydney a copy of the passage in Darwin's Geological Observations 

 on Volcanic Islands, to which reference was made in connection with 

 the discovery reported by him of a " volcanic bomb " in the interior of 

 Australia. The following extract completes the early history of 

 obsidian <: buttons " in Australasia : — 



"Sir Thomas Mitche)ll has given me what at first appears to be the 

 half of a much flattened oval ball of obsidian ; it has a singular 

 artificiaMike appearance which is will represented (of the natural size) 

 in the accompanying woodcut. 



" It was found, in its present state, on a great sandy plain between the 

 Rivers Darling and Murray, in Australia, and at the distance of several 

 hundred miles from any known volcanic regioc The external saucer 

 consists of compact obsidian of a bottle-green colour, and is filled with 

 finely-cellular black lava, much less transparent and glassy than the 

 obsidian. The external surface is marked with four or five not quite 

 perfoct ridgep, which are represented rather too distinctly in the wood- 

 cut." 



A POISONOUS PLANT. 



The Chairman announced that Mr. Rodway had identified a 

 poisonous plant which had killed some sheep and cattle on runs as 

 the Zieria Smithii or "stink wood." 



RECENTLY DISCOVERED TASMANIAN MINERALS. 



Mr. W. F. Petterd, C.M.Z.S., read valuable notes on some recently 

 discovered and other minerals occurring in Tasmania. 1. Aikenite 

 (sulpbatio-bismuthite of lead and copper), Block 291, N. E. Dundas. 

 2, Analcite (hydrated silicate of aluminium and sodium), somewhat 

 abundant in vesicular basalt at the Penguin River. 3. Bismuthinite 

 (sulphide of bismuth), common in acicular crystals associated with 

 tetrahedrite, from the Curtin-Davis group of mines. The tetrahedrite 

 also contains bismuth, which possibly replaces portion of the antimony 

 of that mineral. The associated minerals are mainly chalcopyrite and 

 sidvute. At the Ea«t Hercules mine it occurs in chloritic schist with 

 pyrite and chalcopyrite. At the South Mount Black P. A. it has been 

 obtained from tourmaline and quartz in schist rock. 4. Boulangerite 

 (sulphantimorite of lead). A mineral resembling this comes from Block 

 291, N.E. Dundae. It is evidently a sulphantimonite of lead with 

 bismuth, iron, and copper, the first mentioned constituent giving strong 

 reactions. It is largely noticed with chalcopyrite, arsenopyrite, and 

 pyrite, and is rich in silver. 5. Chalcotrichite (fibrous cuprite) found 

 by Mr. R. Williams at the Colebrook mine. It occurred in capillary 

 tufts of a beautiful crimson colour, surrounded by a thin coating of 

 native copper in the limurite rock. 6. Datolite basic orthosolicate of 

 calcium and boron, samples forwarded by Mr. R. Williams, manager 

 Colebrook mine, N.E. Dundas, being a recent addition to the already 

 long list of minerals known to occur in this island. This is supposed to 

 be the first discovery of the mineral in Australasia. 7. Fayalite (iron 

 olivini) abundant in microscope crystals of a bright red colour in 

 fayalite basalt from the Alexandra battery, near Hobart. 8. Idocrase 

 (a basic silicate of calcium, aluminium, and iron) occurs in considerable 

 quantities at the Hampshire Hills. In some rare instances the crystals 

 are fully lio. in diameter. 9. Ilvarte (a basic ortho-silicate of iron and 

 calcium) obtained, associated with idocrase, from the Hampshire Hills ; 

 embedded crystals sometimes measure up to £in. in diameter. 10. Pala- 



