20 SMITHSONIAN MISCELLANEOUS COLLECTIONS VOL. 58 



AFRICA (Continued) 



Holds that the pneumatolytic theory of tin deposits is untenable and attempts 

 to explain the South African deposits on the hypothesis that they are formed by 

 magmatic differentiation or by the combined action of magmatic differentiation and 

 lateral secretion. The South African deposits are individually briefly reviewed. 



3b. RUMBOLD, WM. R. The South African tin deposits. 



Bi-mo. Bull. Amer. Inst. Mg. Eng. No. 22, 1908, New York, pp. 601-607, figs. 5. Trans. 

 Amer. Inst. Mg. Eng., Vol. 39, 1909, New York, pp. 783-789. 



Describes the Cape Town (Kuils River), Bushveld and Swaziland (Oshoek and 

 Forbes Reef) tin deposits as they appeared in 1904. 



At Kuils River crystallized pinkish-gray cassiterite occurs with wolframite in 

 a 5-foot quartz vein cutting granite. Placers have been formed from the vein. 

 At Bushveld cassiterite occurs with quartz in decomposed granite. 



The Oshoek deposits are stanniferous hornblende pegmatites and placers derived 

 from them. The pegmatites carry garnet, monazite, euxenite, seschynite, and 

 large isolated crystals of cassiterite. In the Forbes Reef deposits cassiterite occurs 

 in an aplite dike and in thin veins cutting schists which carry cinnabar, gold, 

 scheelite, bismuth, monazite, euxenite, aeschynite, copper and iron pyrites, pyrrhotite, 

 margarite and tourmaline. Crystals from the veins when scratched, sometimes fly to 

 pieces like Rupert's drops. 



The description shows a marked resemblance between some of the South African 

 deposits and some of those near Hill City, South Dakota, 



STOKES, RAU>H S. G. See No. 730. 

 3c. VOIT, F. W. Uebersicht liber die nutzbaren. Lagerstatten Siidafrikas. 



Zeitschr. prakt. Gcol., Vol. 16, 1908, Berlin, pp. 191-216. 



A geological study of the economically valuable mineral deposits of South Africa, 



including gold, diamonds, copper, graphite, tin, monazite, iron ores, magnesite, 

 asbestos, etc. 



3d. WESTON, E. M. Tin mining and ore dressing in South Africa. 



Eng. Mg. Journ., Vol. 89, 1910, New York, pp. 411-413, 470-472, 573-574, pis. 8, 

 cross sections 5, maps 2. 



At Embabaan, Swaziland, tin occurs in " the older granite " cutting Archaean 

 beds composed of mica, chlorite and talc schists, with some amphibolite and 

 quartzite. The granite shows dioritic phases. Where tin is most plentiful quartz 

 is almost absent in the granite. The coarsest cassiterite occurs in the granite with 

 pegmatite containing blue, white, or yellow quartz. Some cassiterite crystals 

 appear monoclinic and, where twinned, orthorhombic. Pieces of cassiterite weighing 

 ^4 to % pound are not uncommon and masses of 8 pounds occur. Ilmenite, mostly 

 in fine grains, corundum, monazite, aeschynite, and euxenite in crystals as large 

 as those of the tin ore are found in the debris and in the pegmatite with the 

 cassiterite. Deposits in decomposed granite and pegmatite are worth up to $1.25 

 per yard; residual concentrations and alluvial deposits of great irregularity as to 

 distribution of values, are worked. The fields are not as large as those of Australia 

 or the Malay Peninsula. Suction dredges may prove profitable. Labor is cheap, 

 material high. Between 1600 and 1700 tons of tin ore have been produced, at a 

 profit of 33 5s. 7d. per ton. 



Second article describes mode of sluicing. Corundum and monazite are picked 

 from the coarser concentrates. 



Third article describes the Waterberg deposits, 100 miles north of Pretoria. Tin 

 occurs in sandstone, granite, felsites and shales near contacts. In the northern 

 part of the field the tin is in irregular impregnations in granite; in the southern 

 part it is in pipes. At Zwartkloof decomposed granite carrying about 2s. worth 

 of tin per cubic yard will be hydraulicked. Gives a description of the milling 

 process at the Zaaiplaats and Rooiberg mines. 



See also Cape Colony, Congo, Kamerun, Nigeria, Swaziland, Transvaal, 

 Madagascar. 



