ores, in which tellurides are generally not visible to the eye, are 

 exhibited. In case 128 will be found a fine specimen showing 

 a vein of gold tellurides traversing the rock.* 



In the oxidized ore from near the surface will be noticed a 

 peculiar clay-like form of gold — the so-called " mustard " variety. 

 This appears to be characteristic of the weathering of telluride 

 ores. The tellurium, being very volatile, passes off, leaving the 

 gold in this mustard-like condition. Mustard gold is also found 

 at Cripple Creek, Colorado (see 8624 in case 92). 8438, 8426, 

 9330, and other specimens in the first two rows show this 

 well. 8455 shows a chocolate tint, also rather characteristic of 

 the weathering of tellurides. The metallic mineral showing in 

 this specimen is pyrite, not telluride of gold. A series of ores 

 from various mines is exhibited, in which the metallic mineral 

 showing is generally pyrite. 



8509, Kalgurli Mine ; a light-coloured ore with specks of 

 titaniferous iron scattered through it. Titaniferous iron appears 

 to occur in most of the ore and country rock. 



8513, Grreat Boulder Mine, has been cut to show the brecciated 

 character of the ore. 



8470, Block 45 ; calcite with calaverite, one of the rare instances 

 in which gangue minerals accompany the Kalgoorlie ore. 



Auriferous quartz from Mallina, Mount Ida, Coolgardie, 

 Marble Bar, Talgoo, Pilbarra, Menzies. the Murchison, and other 

 localities. 



1432, Lake Austin ; gold with gypsum. 



8796, 8476, Coolgardie ; gold with Iwrnblenie. 



1430, Lake Austin ; gold on lydian stone. 



9562, Donnybrook ; filamentous gold in pulverulent material. 



Kanowna Lead. — Eich gold was found here beneath a false 

 bottom of the travertine which is found covering large areas in 



* The mode of occurrence at Kalg-oorlie is very different from that at Cripple Cr^ek^ 

 Colorado (see pag:e 105). It should he home in mind that there is, at present, no reason 

 for believing that any particular kind of rock is more favourable to the occurrence of 

 tellurides than another, and prospectors should rather aim at identifj'ing the minerals 

 themsel\es. 



