394 ZINC AND LEAD DEPOSITS OF BROKEN HILL. 



same mineral was found by Mr. White* in the cave earth in the 

 form of small lumps. Pyritc and Chalcopyrite occur in very 

 small quantities with the blende and galena in the crystalline 

 limestone below water-level. 



Ccrussitc is probably the commonest mineral in Kopje No. 

 I, but it was not found in Kopje Xo. 2. A little is present in 

 Kopje No. 3. The mineral occurs in magnificent crystal aggre- 

 gates encrusting the numerous cavities in Kopje No. i. These 

 cavities are sometimes several feet in diameter, and often con- 

 tain nothing but cerussite. The mineral is present intimately 

 mixed with hemimorphite, iron oxide, quartz, etc., in the pale 

 brown and whitish rock which forms the larger part of the 

 gossan right at the surface. f Sometimes the mineral is stalac- 

 titic, as was observed by Mr. Spencer. | 



Calamine (zinc carbonate) is present in very large mam- 

 millated masses in the phyllite and limestone of No. 2 Kopje, 

 apparently being associated there with no other zinc or lead 

 minerals. It also occurs rather commonly encrusting the 

 cavernous surfaces of Kopjes i and 2, and occasionally asso- 

 ciated with cerussite and liemimorphite in the crystal-lined 

 cavities in Kopje No. i. 



Hydrozincitc is beautifully developed in mammillated and 

 rosetted crusts infilling cavities and seams in Kopje No. 2. It 

 is not uncommon on the exposed surfaces of Kopjes i and 2 

 as an amorphous crust. The hemispherical soft, white and 

 earthy masses believed by Mr. Spencer§ to be hydrozincite, 

 were found in several instances to be well developed in Kopje 

 No. 2. 



Hemimorphite (zinc silicate) is largely present in Kopje 

 No. T. forming thick, partly crystallized and somewhat stalactitic 

 crusts in cavities, some of which are large and completely lined 

 with that mineral. Sometimes it is well crystallized. Often it 

 is associated with cerussite or calamine and cerussite. Sky-blue 

 hemimorphite occurs infilling smaller cavities. Perhaps the 

 chief development of this mineral is that which forms an inti- 

 mately intermixed aggregate with cerussite, quartz and iron 

 oxide,|| and constituting the bulk of the gossan of Nos. i and 3. 

 It also lines cavities in No. 3. A little doubtful hemimorphite 

 occurs in cavities lined with other minerals in Kopje No. i, and 

 it is " present in crystallized crusts on the bones and on the 

 bone-breccia in the cave."^ 



Pyromorphite mostly occurs with tarbuttite in Kopje No. 2 

 in. the extremely beautiful crystal-lined cavities. Like the tar- 

 buttite, it is deposited on spongy limonite. Exceptionally beau- 

 tiful bright-green crystals in loose aggregates are seen lining 

 cavities in Kopje No. 2. These sometimes have no associated 



* White he. cit., vol. vii. p. 17. 



f Spencer, loc. cit., p. 1. 



J IhicL, p. 36. 



§ Ibid., p. 35. 



i' Ibid., p. 34. 



ilbid., p. 35. 



