ZINC AND LEAD DKFOSITS OF BROKEN HILL- 395 



tari)uttite. and almost continuously line cavities several feet in 

 diameter, thickly covering parts of the cavity. A little pyro- 

 morphite was found at the surface of Kopje No. i, and some 

 occurs in a drive near the bone cave. PAmorphous pyro- 

 morphite in curious very pale brown growths of small size was 

 noted in small cavities in Kopje No. 2. 



Hopeite was only noted in Kopje No. i, where in the bone 

 cave it forms beautiful crystallized coatings* more or less com- 

 pletelv lining the cave as it existed when brokeiii into. The 

 thick mud and bone-breccia of the floor has plainly at some time 

 subsided in part, so that at present the roof and floor of the lower 

 cavity are composed of bone-breccia ; this is thickly covered with 

 vanadinite and hopeite resting directly on a very thin, minutely 

 crystalline crust of ?tarbuttite and Phemimorphite. The 

 corroded form of hopeite occurs as a thick encrustation on one 

 wall of the cave. In three other places in Kopje No. i a little 

 hopeite has been found either with or close by mineralized bones 

 ( in one occurrence the mineral was only doubtfully determined, 

 and in one other the mineral has been removed). 



Parahopeitc is so far the rarest of the zinc phosphates at 

 Broken Hill. It occurs m small rosettes in the highest part of 

 the bone cave, and perhaps to a very small extent in a drive in 

 Kopje No. 2. In the Rhodesia Museum is a specimen of coarsely 

 crystallised parahopeite in limonite. It is believed to have come 

 from Kopje No. 2. 



Tai'buttitc is chiefly developed in Kopje No. 2. occurring in 

 magnificent crystal coatings of considerable extent and various 

 thicknesses in the numerous cavernous spaces of the dark-brown 

 cellular limonite which occurs in the central part of the Kopje. 

 In most instances it is associated with pyromorphite. A little 

 tarbuttite was noted crystallized upon descloizite in Kopje No. i 

 and in Kopje No. 3 ; a small development is also recorded from 

 the cave, from whence it was detected by 'Mv. Spencer J as '' very 

 thin and minutely crystallized crusts on the hopeite specimens 

 and on some of the bones." Tarbuttite was not noted in associa- 

 tion with the fresh unaltered limestone. 



?Go3larite. — A white, ]:)owdery mineral associated with 

 blende, and encrusting that mineral and small patches of a wall 

 of a lower drive in Kopje No. i, is^believed to be zinc sulphate, 

 but unfortunately the sample was lost in transmission. 



Dc';cloisite is present in Kopje No. 3. occurring there in 

 rather large aggregates of crystals, thin seams and crusts lining 

 or infilling small fissures in the limestone and in small cavities 

 6 to 8 inches across, filled with coarsely crystallized descloizite on 

 a surface of massive descloizite. It is associated with a little 

 tarbuttite, etc. The mineral occurs as thin encrustations on 

 portions of the surface of Kopje No. i associated with calamine, 

 and close by an accumulation of mineralized bones. 



On certain joint surfaces of the limestones containing cala- 



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



J Spencer, loc. cit., pp. 22, .30 and 38. 



