32 T. S. Hart : TJie Mineralogical Characters 



veinstone from Gelantipy quoted in the same report gave, in dif- 

 ferent samples, up to 71 oz. of silver, but under 4dwt. of gold per 

 ton in the highest assay. 



At St. Arnaud bournonite occurs, and in the surface stone 

 anglesite, cerussite, pyromorphite, mimetite, embolite and native 

 copper. 



3. Auriferous antimony ores. — Stibnite is only found in small 

 quantities in the ordinary quartz reef, as in the instances already 

 quoted. There are, however, a series of lodes in which it is the 

 leading metallic constituent. These are mainly in the Silurian 

 area of Central Victoria, as at Costerfield and Ringwood, but they 

 are also found in Ordovician rocks, as at Sutton Grange, at 

 Dunolly, and between Coimaidai and Gisborne. In any question 

 of their origin, then, no importance could be attached to the 

 association with Silurian rocks. Krause mentions that the 

 Costerfield ore has given assays as high as 9oz. gold and 80oz. 

 silver per ton (5). 



The other minerals found with the stibnite are not many nor 

 abundant. Bournonite, cuproplurabite, and chalcostibite are 

 noticed as rare at Costerfield (1). The few occurrences of schee- 

 lite in Victoria are not in association with the antimonial ores, 

 though this mineral is found with them at Hillgrove, N.S.W. 



Cervantite is the common alteration product of these ores, but 

 kermesite and senarmontite are found in small quantity at a few 

 places, and valentinite soniewhat moi"e frequently. 



4. Chalcopyrite. — This mineral again is in small quantity in 

 the ordinary type, though it frequently appears with increasing 

 complexity. At the Thompson River Copper Mine it occurs 

 with other copper minerals. A series of assays from this mine 

 (13) showed only a trace of gold, and silver only as high as 6oz. 

 per ton. It is noteworthy that these ores contain up to 3| per 

 cent, nickel. 



While this ore must then be regarded, so far as tliese assays go, 

 as not a gold producer, it will be seen by examples already quoted 

 that the addition of chalcopyrite to the minerals of the ordinary 

 reef is at least sometimes favourable, though there is nothing to 

 show that the increase in gold is derived from the chalcopyrite. 



5. Siderite-chalcopyrite. — A vein composed mainly of these 

 two minerals, with smaller quantities of pyrite, arsenopyrite. 



