BY VV. F. PETTERD, C.M.Z.S. 141 



262. Pyrargyrite (Silver Sulphantimonite ). 



Ruby silver ore has recently occurred at several mines, 

 notably at the Magnet, where it is not by any means rare, 

 in patches and blebs in close association with galenite. 

 The mineral is sometimes surrounded by frondose and 

 granular native silver, and the combination, needless to 

 say, adds materially to the silver assay value of the ore. 

 At the Mt. Stewart Mine it occurs sparingly, and in small 

 vughs little nests of micro-rhombohedral crystals have been 

 detected, which are probably this mineral. At the Mt. 

 Farrell Mine it has been noticed embedded in galena; also 

 at the Confidence Mine near Waratah, and at the Hercules 

 Mine, Mt. Read, it has been seen in micro-crystals attached 

 to filaments of native silver. Reported to have been found 

 at the Oonah and British-Zeehan Mines at Zeehan. 



The light ruby silver ore (proustite) is sometimes associ- 

 ated with the pyrargyrite ; the latter appears to be the 

 more often noticed, but the exact determination of the 

 species has not been made in the majority of occurrences. 



At the Magnet Silver Mine this mineral has recently 

 been obtained in small, but perfectly-formed, character- 

 istic rhombohedral crystals nestling in cavities in the lode 

 gangue associated with galena and blende in the southern 

 working of the mine. They are dull-black in colour, due 

 to tarnish, but readily give the bright-red streak, as well 

 as the conchoidal fracture, when broken. The mineral in 

 its compact and investing forms is not by any means rare, 

 but the crystals are extremely so ; in fact, they appear to 

 have been first detected in this State. 



263. Pyrite (Sulphide of Iron). 



With the exception of quartz, this is, in all probability, 

 the most w^idely distributed and abundant mineral in 

 nature, and it is especially plentiful in many portions of 

 this State. It is commonly known as iron pyrites in contra- 

 distinction to copper pyrites ; and also as mundic, a Cornish 

 term, w4iich is now universally employed. The composition 

 is iron disulphide, with occasionally a few atoms of iron 

 replaced by copper, in which case it may be termed a 

 low-grade copper ore, the empirical composition being 

 S 53'4, Fe 46"6. The large proportion of sulphur renders 

 '"•t of the utmost importance in the process of pyritic 

 smelting, and also in the manufacture of sulphuric acid, 

 more particularly in the production of superphosphates. 

 Pyrite crystallises in the isometric system, and is com- 

 monly found in well-defined cubes, which often reach a 



