14 THE MINERALS OF TASMANIA. 



as arsenical mundic. When struck with the hammer or 

 pick, it emits the characteristic garlic odour of arsenic. 

 It is isomorphous with marcasite, and like that mineral, 

 crystallises in the orthorhombic system. It is the parent 

 of many of the secondary minerals which follow its oxida- 

 tion, such as scorodite and other arsenates which are 

 formed by association with decomposed arsenides and sul- 

 phides containing copper and even lead. Mispickel is still 

 mined in Cornwall and Devonshire, England, for the pro- 

 duction of " white arsenic," which is obtained by roasting 

 the crude material. In all tin-mining countries this 

 mineral is abundant, as it is a constant companion of 

 cassiterite, and is presumed to have been produced by the 

 same solfataric and pneumatolytic agency. The emana- 

 tions from an acid magma have been the cause of the 

 alteration of granite and adjacent rocks through deposit- 

 ing this mineral with others so characteristic of tin lodes 

 and pegmatites. As occurring in this island, it is usually 

 in an amorphous condition, and when in the crystallised 

 state the individual crystals are not so well-formed as 

 those which have commonly occurred in other parts of the 

 world. It is supposed to be a deep-seated mineral, as it 

 shows vertical persistence in depth. At Mt. Bischoff it is 

 too abundant from a tin-mining standpoint, as its con- 

 tamination of the ore is a serious cause of trouble and 

 expense. The same applies to other centres of the industry, 

 notably at the Cleveland Mine, Heemskirk, and Mt. Rex. 

 At Mt. Ramsay it is plentiful with native bismuth in 

 amphibole; also at Mt. Pelion, south of the Surrey Hills 

 block of the Van Diemen's Land Co. At the Penguin 

 River it occurs in the old mines now abandoned. The 

 analysis of the mixed ore from this locality is said to have 

 given appreciable quantities of nickel, cobalt, and silver. 

 At the goldfields of Mathinna, Lefroy, and Beaconsiield 

 it occurs in the auriferous quartz reefs ; on the southern 

 slopes of Mt. Wellington a limited occurrence has been 

 reported assaying up to 15 per cent, of cobalt ; about 

 Lyndhurst and east of Mt. Cameron it is abundant, and 

 commonly highly auriferous ; and at the Upper Scamander 

 River is is equally abundant, and at this locality more 

 often wholly or partially altered to scorodite. At the Mag- 

 net Mine it occurs sparingly, but in beautifully-formed 

 crystals and trillings. At the Colebrook Mine it is found 

 intermixed with axinite and pyrrhotite. At many other 

 localities the mineral occurs, but does not, so far as known, 

 present any features of special interest. Occurs as minute 



