51 



measures an eighth of an inch across. The pretty blue quartz CaEC 59. 

 entangled in the ironstone on -which these crystals occur should 

 be noted. 5545 shows a great many six-sided prisms, but is dull 

 and opaque-looking. 



Of the kaolin specimens, 48, with its thick masses of iodide, 

 will be noticed. Of the ironstones, it may be said that they 

 sometimes contain the silver minerals right through their mass, 

 or ou every side, not only on the surface exposed to view. 

 Other minerals associated with the iodide are cerussite (1362) 

 and calamine (1060 — the colourless mineral). Further specimens, 

 and in particular 3116, Central Mine, will be found in case 127). 



Emholite ; chloro-bromide of silver. This mineral is of a 

 bright green colour when first exposed, but rapidly blackens 

 unless kept in the dark. Many of the early specimens have been 

 ruined in this way.* The Museum possesses a fine collection of 

 this beautiful mineral. At Broken Hill it is genei^ally found in 

 waxy-looking little crystals, showing faces of the cube, with the 

 angles truncated by those of the oclahedron. 5531 is a magnifi- 

 cent specimen of manganiferous ironstone on which are seated 

 numerous very perfect crystals of embolite sometimes measuring 

 nearly a quarter of an inch across. 5528, 5530, and others, are 

 spongy masses of embobte. Embolite is also found encrusting or 

 associated with quartz (4102), kaolin (4061), cerussite (1378), 

 calamine (1198, 1147), azurite (1200), galena (1196), malachite 

 (1230). 



In the first half of this case are exhibited ores from Silverton, fjaae gl 

 Thackaringa, Umberumberka, and other localities in the Barrier 

 Eange, worked in the early days of silver-mining in this district, 

 but now for the most part abandoned. The ores consist 

 principally of galena and cerussite but rich chlorides or chloro- 

 bromides sometimes occur. 



Thackaringa.— (jrd\Qna,,^jT\te% (iron and copper), blende chaly- 

 bite, cerussite and quartz occur. The peculiarly fine-grained 

 character of the galena should be noted (1475). 



* Photographers will remember that their art depends upon the action of light upon 

 certain silver salts, such as the bromide and chloride. 



