ECONOMIC GEOLOGY 479 



A few salt-pans are situated upon the older format- 

 ions namely, Groot and Klein Chwaing in Vryburg, 

 and Matsap in Hay. 



In Central Cape Colony the only salt-pan of note is 

 that at Maraisburg, on Beaufort beds. In the very im- 

 portant Zwartkops Pan, near Port Elizabeth, the salt 

 has probably been derived from the clays of the Uiten- 

 hage series. 



Along the coast salt is found in several localities 

 where an arm of the sea has been shut off by a sand 

 dune namely, at Port Nolloth, Yzerfontein Point 

 (Malmesbury), and Papen Dorp (Piquetberg), the last 

 named being among the sand dunes. 



Gypsum is found below the clay forming the floor of 

 the Port Nolloth Pan, that at Klip Fontein's Berg in 

 Clanwilliam, and the Zwartkops Pan. That the salt 

 obtained in the Colony is generally free of any marked 

 impurity is shown by the analyses of Dr. C. Juritz. 1 



Tin. Tinstone or cassiterite has been found at several 

 points in the Western Province both in veins and 

 as alluvial deposits. At Annex Langverwacht, near 

 Kuil's Kiver, 2 the cassiterite occurs in veins of quartz 

 and greisen in the granite of the Bottelary-Stellenbosch 

 mass, close to its junction with the Malmesbury slates, 

 and also disseminated through the adjoining granite. 

 It is associated with wolfram and tourmaline, and by 

 the denudation of the ridges a considerable deposit of 

 tin-bearing gravel has been formed on the sloping ground. 



1 " On the Composition of the Salt from some Colonial Salt-pans," 

 Agric. Journ. C. Colony, Nov., 1908, p. 648. 



2 H. Griffiths, Journ. Chem. Min. and Metall. Soc. S. A., viii., 1907, 

 p. 167. 



