50 



Case 59. "When in Ijaolin, native silver always seems to assume a leafy 



form, of which there are several examples. Not uncommonly it 

 occurs in ironstone ; of this, 5539 is a fine instance. 



Tet another interesting occurrence is that on native copper. 

 1268, consists of fragments of white quartzite entangled in 

 native copper, on which the silver is scattered in crystalline 

 groups. 1359, while consisting principally of massive carbonate 

 of lead, shows the same two native metals associated.* 



5540, ferruginous quartzite, shows chloro-bromide with native 

 silver seated on it or growing from it. It will be noted that the 

 silver minerals seem to occur only on the ferruginous patches. 



Dyscrasite, antimonide of silver. This mineral occurs princi- 

 pally in the Consols Mine, where it has been found in masses 

 sometimes weighing over a ton : it has frequently been mistaken 

 for native silver. Photographs of some of these large masses are 

 exhibited on the pillar close by. The Museum collections include 

 a large block, which is not publicly exhibited. It occurs 

 associated with calcite and chalybite, together with pyrargyrite, 

 cobaltite, &c. (8580, 6905, and others). An antimonial silver- 

 chloride ore, found in this mine, has undoubtedly resulted from 

 the alteration of dyscrasite — 5293, 5295. 



8765, 8769, Consols Mine ; pyrargyrite. 

 1358, Consols Mine ; sternbergite, associated with calcite and 

 chalybite. 



5497, Consols Mine ; fahl-ore, associated with galena and 

 chalybite, and assaying 6,500 oz. silver per ton. 



7587, Consols Mine, stromeyerite. 



lodargyrite, iodide of silver,t is generally found as a very soft, 

 waxy, lemon-yellow encrustation on kaolin or ironstone. 



5527, Block 11, best shows the crystalline form, the six- 

 sided prismS being very apparent ; one of the larger crystals 



* A fine specimen (5205) of native silver welded on to native copper, fron Lake Superior, 

 will be found in case 84. 



t The iodine, in iodargyrite, and the bromine in erabolite, can be readily expelled and 

 rendered visible by surrounding a fragment of the mineral with bisulphate of potash, and 

 fusing it in a glass tube closed at one end. 



