WHOLE VOL. SKELETAL REMAINS OF EARLY M AN— IIRULICKA I35 



Marshall Hole and others, as well as on other material for the opportunity of 

 examining which we are indebted to Mr. White and to Mr. F. G. Colville. 



The Rhodesian Broken Hill Mine is situated about 150 miles north of the 

 Kafue River in North-Western Rhodesia. It contains extensive zinc and lead 

 deposits which have a prominent outcrop in the shape of two small hills or 

 "kopjes" rising out of a " vlei " or swampy flat. The surrounding country is 

 chiefly limestone, which is associated, in proximity to the ore-body, with schistose 

 rocks, evidently altered sandy and shaly sediments, together with crushed bands 

 of the limestone itself. There is granite not many miles distant, but the ores do 

 not appear to have any direct connection with an igneous rock ; they seem rather 

 to be related to faulting and shearing of the limestone at its junction with the 

 schists. Surface specimens of the limestone are usually somewhat coarsely crys- 

 talline, and white or grey in color with few impurities save quartz. Lower down 

 in the workings they are often black or reddish in color and closely resemble 

 the Carboniferous Limestone of Somersetshire. Under the microscope, however, 

 they differ in toto. having a foliated structure in even the most compact-looking 

 specimens. It is probable therefore that the sugary appearance of the outcropping 

 rock is due to some form of surface alteration. It cannot be attributed to pres- 

 sure or contact metamorphism, as it would in that case be just as apparent below 

 ground as it is above. The limestone is highly magnesian and sometimes ap- 

 proaches a true dolomite in composition. No definite silicate minerals can be 

 detected under the microscope. 



The feature of the ore-body with which we are now chiefly concerned is the 

 extraordinary accumulation of mammalian bones in No. i Kopje. Beautifully 

 crystallized phosphatic minerals have also been found in No. 2 Kopje, but al- 

 though it would seem a natural inference that they are due to the interaction of 

 the metalliferous solutions with the lime phosphate of bones, none of the latter 

 have been met with. The amount of bones in No. i Kopje is enormous. They 

 occur in the central part of the kopje and almost continuously beneath it, below 

 the level of the surrounding flats. It would appear that the bone deposits repre- 

 sent the infilling of a large cavern in the limestone, perhaps with a kind of 

 swallow-hole leading down from the top of the kopje, though there is no actual 

 opening at the present time. It is diflficult from the data at present available to 

 determine with an\' certainty the relative ages of the different layers of bones, 

 but their accumulation must have taken a very long period of time. There are 

 masses of bones almost free from other substances, and there are interspersed 

 muddy layers containing zinc compounds, but free from bones. Much of the 

 material, however, which shows no large bones, yields on disintegration innu- 

 merable bones of rats, .shrews, birds, etc. The bones are in nearly all cases partly 

 or wholly converted into zinc phosphate (hopcite?). They are therefore truly 

 fossil, the organic matter having disappeared and having been completely re- 

 placed by mineral substances. Vughs in the deposit are often lined with mag- 

 nificent crystals of the rare mineral hopeite and they also show at times more 

 or less dendritic coatings of a substance which at first was taken for amorphous 

 zinc phosphate, but which is rich in vanadium and may really be a calcium vana- 

 date. The new triclinic zinc phosphate " tarbuttite " occurs in No. 2 Kopje with 

 cerussite, hemimorphite, hopeite. pyromorphite and vanadinite or descloizite, and 

 does not seem to be found in the bone deposit. 



The bones make up vast accumulations of isolated broken fragments. Whole 

 bones are the rarest exceptions, and are exceedingly difficult to extract even 

 II 



