276 



C. ANDERSON. 



The three hand specimens seem to be nodular in origin, 

 and the best crystals are found inside hollow nodules. In 

 two of the specimens, which may be called A and B, the 

 azurite is seated on a dark, gossany mixture, consisting 

 mainly of limonite with small quantities of cerussite and 

 malachite. In A the malachite is apparently more recent 

 than the azurite which it partly pseudomorphs; malachite 

 also occurs on this specimen as small spherules. On B 

 malachite is found as little globular masses, umber coloured 

 externally and dark green inside ; it was at first thought 

 that these might be atacamite, but they gave no reaction 

 for chlorine. Specimen O is larger than the others and the 

 crystals of azurite are quite fresh and show no signs of 

 alteration to malachite, which appears as bright green,, 

 fibrous tufts amongst the cerussite. A typical vugh in this 

 specimen is lined with a crystalline crust of cerussite on 

 which the azurite rests; the walls of the vugh are com- 

 posed of a hard, siliceous shell, jasperoid in part, and 

 traversed by veinlets of azurite and cerussite in a direction 

 at right angles to the inside surface of the vugh. The 

 nodules on specimen O are coated externally by a yellowish 

 powder, which contains lead in large amount; this coating 

 is probably identical with a substance which sometimes 

 forms fairly large masses at Mineral Hill and which was 

 found by Mr. J. 0. H. Mingaye, Analyst to the Department 

 of Mines, to contain 165 oz. silver, 51 per cent, lead, 5*4r 

 per cent, antimony, and a trace of gold. It seems to be 

 an impure mixture of massicot and bindheimite. Cuprite 

 and cerargyrite were not observed in immediate association 

 with the azurite, but crystallised specimens of these 

 minerals from the Iodide Mine are in the Museum Collec- 

 tion ; these and the cerussite, which is mostly in aggregated 

 crystals twinned on m (110), will be described in another 

 paper now in course of preparation. 



