BY W. F. PETTERD, C.M.Z.S. 13 



argentit-e have been detected implanted on siderite and 

 other veinstone. 



In Professor J. W. Gregory's report, entitled "The 

 Mount Lyell Mining Field " (Aust. Inst. Min. Eng., Mel- 

 bourne, 1905), the following paragraph occurs, which 

 records the occurrence of argentite in association with 

 chalcocite at the Mt. Lyell Mine: — "More important 

 shoots of the richer ores have been found on the footwall 

 side of the mine. The largest, known as the Mt. Lyell 

 Bonanza, was discovered and worked out in 1904; it 

 yielded 850 tons of ore. which was sent to London and 

 sold for £105,000. This bonanza was found between the 

 pyrites mass and the lower continuation of the hematite 

 of the Iron Blow. It consisted of a vein of copper glance 

 (redruthite Cu* S) and bornite, with fahl-ore and argentite 

 (silver glance, Aga S). It was found in a drive from the 

 No. 4 tunnel. The entire shipment averaged 1011 oz. of 

 silver to the ton, and one specimen which was knocked ofi 

 by Mr. Lewis, the Attorney-General of Tasmania, and was 

 assayed by the Tasmanian Government assayer, is quoted 

 by Peters as yielding 8765 oz. of silver and 45 oz. of gold 

 to the ton and 19 per cent, of copper. Some specimens 

 assayed nearly 50 per cent, silver. As the vein was fol- 

 lowed downward it increa&e'd in thickness, being in places 

 2 feet in width. The discovery of this body of rich ore 

 was of great importance in the history of the field, as it 

 had a considerable influence in securing the capital nece& 

 sary for the development of the mine.'' 



25. Arsenic, Native. 



In hemihedral crystallisations, with radiated internal 

 structure ; colour almost tin-white, tarnishing black. 



Locality: East Bischoff Mine; in lowest level, North 

 Valley lode, Bischoff, in blades between laminae of siderite 

 with fluorite, various pyrites, and black sphaierit^ 

 (Ulrich). 



26. Arsenolite f Arsenious Acid or White Arsenic). 



A single lump was obtained at one of the old mines at 

 the Penguin, associated with arsenical copper, melaconite. 

 and a little native copper. 



27. Arsenopyrite fSnlpharsenite of Iron). 



This is better known under the vernacular name of 

 " mispickel," and belongs to the class of sulphides some 

 times termed the pyritoids. It is also known to miners 



