172 THE MINERALS OF TASMANIA. 



316. Stibnite (Sulphide of Antimony). 



This is the principal commercial ore of antimony, a 

 metal which, with arsenic and bismuth, forms an alliance 

 of brittle metals. It is usually found massive, with a dis- 

 tinctly bladed habit, is very brittle, and may be mistaken 

 for bismuth sulphide. It crystallises in the orthorhombic 

 system. It may be recognised by its perfect longitudinal 

 cleavage and by horizontal lines on the cleavage surface. 



It has occurred in massive irregular bunches of con- 

 siderable size in quartz reefs at Lefroy, with the usual 

 columnar structure, notably at what was known as the 

 Orlando Gold Mine. It did not carry the precious metal 

 to any appreciable extent. In very limited quantity near 

 Mt. Claude ; in schist in apparently fair quantity at Port 

 Davey ; as a lode at Hall's Creek, near Lynchford, of very 

 fair quality : found as a diminutive vein at Rosebery. 

 Reported to occur at Mt. Bischoff and North-East Dun- 

 das, but in both instances the antimonial mineral was not 

 stibnite. 



317. Stilphnosiderite (Hydrated Peroxide of Iron). 



Occurs of a dark blackish-brown colour, with a con- 

 ehoidal fracture, shining and brittle. It is generally found 

 in a stalactitic form, or as a varnish-like coating on limon- 

 ite or manganese minerals, more particularly on psilome- 

 lane. 



Central Dundas Mine; rarely, Mt. Bischoff; lining 

 vughs of ironstone with cuprite, Mt. Lyell ; Central Bal- 

 strup Mine, Zeehan, coating masses of limonite, which 

 are commonly of stalactitic form. 



318. Strigovite (A Basic Silicate of Iron and Aln- 



mininni). 



A chlorite-like mineral, consisting of a black shining 

 aggregate of minute plates, in the fractures decomposed 

 to brown. Occurs as a narrow band a few inches wide in 

 granite near the Great Republic Tin Mine, Ben Lomond 



319. Stromeyerite (Suliihide of Silver and Copper). 



When pure this mineral contains about 52 per cent, of 

 metallic silver. It crystallises in the rhombic system, and 

 is isomorphous with copper glance. In colour it is steel- 

 grey, with a metallic lustre and shining streak. It is soft 

 and perfectly sectile. It occurs disseminated, with bornite 

 and chalcopyrite, in a quartz matrix at Mt. Lyell. Assays-. 



