76 



4032, BetliuDgra : Avith structure somewhat resembling '' cone- 

 in-cone." (See page 173.) 



2733, Oberon : stalactitic form. 



2723, Tingha : hollow concretionary nodule occupied by white 

 clay. 



2920, Barrier Range : forming a pseudomorph after chalybite. 



4174, Mount Gipps, Barrier Range : pseudomorphous after 

 lenticular crystals of chalybite. 



895, Eockley : large cube after pjrite. 



2709, Wallerawang : concretionary variety. 



7817, Crookwell: fibrous variety, 



4083, Pooncarie : oolitic variety. 



10139, between Sunny Corner and Piper's Plat : iridescent 

 stalactitic limonite. 



Some of tbe specimens illustrating structural geology in case 

 113 consist of limonite. 



In compartments at the end of cases 64 and 66 respectively, 

 are block specimens of stalactitic limonite and of limonite 

 pseudomorphous after chalybite from Broken Hill. 



In pyramid case 106 is a mass of bark, stick, &c., encrusted 

 with limonite, from the base of a living rock fern, which was 

 itself parti,ally replaced by oxide of iron ; from Mount Victoria. 



The stalactitic, concretionary, and pseudomorphous forms 

 assumed by hydrous oxide of iron are evidence of the facility 

 with which iron salts are dissolved and re-deposited by water. 



Jia^ybite. Carbonate of iron. In small quantities this is not an 



uncommon mineral. It is sometimes found crystallised, when 



its cleavage and appearance are not very unlike calcite. Colour, 



opaque white to buff or red. 



There is nothing whatever in the appearance of chalybite to suggest 

 that it contains up to sixty per cent, of metallic iron. The most 

 characteristic test is to gently heat a small fragment in a piece of 

 glass tubing; the mineral flies to pieces {decrepitates) and blackens; 

 on shaking it out, it will be strongly attracted by a magnet. 



