BY W. F. PETTERD, C.M.Z.S. 77 



to represent the finest discovery of its nature that has 

 occurred in this island. At the White Hawk Mine, east of 

 Mt. Farrell, the lead ore is associated with milk-white 

 calcite, and is unusually poor in silver. At the Thomas' 

 Blocks Mine, south of Murchison River, quite an unusual 

 quantity of fluorite occurs, which indicates the proximity 

 of the mine to the granite of the region. Tlie spar is 

 remarkably pale in colour, in some instances almost, if 

 not quite, white. The associated gangue is quartz, with 

 less siderite than is usual. The characteristic gangue or 

 lode-matrix of the silver-lead mines throughout the island 

 is a compact form of siderite or carbonate of iron, which is 

 occasionally varied by a small quantity of quartz and 

 rhodocrosite. At the Magnet Silver Mine somewhat fine 

 pseudomorpbs of the mineral under consideration after 

 sphalerite, have occasionally occurred. They are usually 

 in irregular groupings, with drusy surface and glimmering 

 lustre. The occurrence of galenite at this mine is 

 of special interest, since it illustrates what is t'o 

 all appearance a deep-seated lode; as is shown by 

 the laminated arrangement of the seams of ore on 

 either side of a central crustification. At the Rex Hill 

 Tin Mine the surface w^orkings contained a considerable 

 quantity of galena, associated with blende and chalco- 

 pyrite. 



The antimonial minerals zinkenite and jamesonite are 

 comm-on associates, as is instanced by the comparative 

 abundance of the former at the Magnet Mine, and the 

 latter at the Madame Melba, Spray, Comet, and other 

 mines. At the Stirling Valley a coarse cubical variety 

 occurs, associated with pyrite, which is in crystalline 

 masses. It occurs near Deloraine with barite and dolomite, 

 in laminated bands, alternating with sphalerite. In the 

 auriferous districts of Beaconsfield, Lefroy, and Mathinna 

 galena is of common occurrence in the quartz reefs, inter- 

 mixed wit'h arsenopyrite. sphalerite and pyrite, and more 

 rarely with stibnite. At the abandoned mines at the 

 Penguin it occurred with nickel and cobalt minerals. 



The geological age of the Zeehan and adjacent Dundas 

 silver-lead regions is Cambro-Ordovician to Middle 

 Silurian. Tlie prevailing rock is an argillitic slate, with 

 sandstone, which in places contains numerous testacean 

 fossils. It is bounded on the west by serpentine and the 

 stanniferous granite of Heemskirk, on the north-east by 

 similar rocks, and on the east and south-east by the older 

 rocks of the Read district. The lodes, which are very 



