44 THE MINERALS OF TASMANIA. 



It is noticeable that, while the variety under review is 

 invariably associated with the chromate of lead, the 

 common type is rarely if ever obtained in the vicinity. 

 It is always opaque, with a shining lustre, but not ada- 

 mantine. The colour is canary-yellow, with an occasional 

 tinge of red where the crystal has impinged upon the 

 chromate. The tint does not vary to any serious extent, 

 although paler examples are occasionally met with. It is 

 a most attractive mineral, and soon arrests attention. 

 Its most constant feature is its crystallisation in flattish 

 frondose and spear-headed groups, twinned by repeated 

 angles across different faces of the prism (110). The 

 striated faces of the twinned groups are the brachyprisms 

 Oil and 013; these are commonly deeply grooved, afford- 

 ing a most interesting leaf -life and unfamiliar appearance. 



This variety is perfectly distinct, both as regards colour 

 and habit of crystallisation. Moreover, intermediate 

 variations between it and the normal type have not been 

 met with. It is undoubtedly one of our most attractive 

 and typical minerals. Under the blowpipe it gives 

 reactions for chromic acid. 



6S. Cervantite (Dioxide of Antimony). 



Abundant as a result of the decomposition of anti- 

 monial minerals, usually as a thin yellow coating on 

 jamesonite, galena, and on veinstone. It is usually mas- 

 sive. Madame Melba, Comeb, and Maestrie's Broken 

 Hill Mines at Dundas are prominent localities. It also 

 occurs in small quantity at several of the silver-lead mines 

 in the Heazlewood district and at Zeehan. It has occurred 

 in small quantity in a quartz reef known as Ragged Jack, 

 about 9 miles east of Deddington, with pyrites, galena, and 

 stibnite. 



H9. Chabazite (Silicate of Aluminium, Sodium, and 

 Calcium). 



This abundant zeolite occurs in the cavities of vesicular 

 basalts. The obtuse rhombohedral crystals are usually 

 well-formed, clear, and colourless. Abundant near the 

 railM^ay bridge which crosses the Hellyer River. Of small 

 size, but well-formed groupings, Springfield ; associated 

 with other zeolitic minerals, olivine and calcite, Sheffield 

 and near Mt. Claude ; with ferro-calcite, Lefroy ; occurs 

 abundantly with vesicular basalt at Mt. Pelion and vicin- 

 ity ; the crystals are well-developed and in fine group- 

 ings, often lining the cavities. Rounded, waterworn 



