Editorial Comment. 1 1 1 
and Californian deposits, again sank until in L890 it was 
about $100,000,000. But by 1893 the South African"; mines 
had raised it to about $150,000,000, and the estimate for the 
present year is $200,000,000, or nearly twice as great as was 
ever known before they were discovered. 
The geology of* South Africa may be outlined as follows: 
<1. Recent deposits of alluvial and of seolian origin, con- 
sisting largely of "laterite" or brick-earth. 
c. Karoo formation, of the date of the lower Mesozoic of 
Europe and found chiefly in the Cape Colony, Natal, South 
Transvaal and Orange Free State. In this occur the coals of 
the region which supply the fuel for the gold mines. 
//. Gape formation. Shales, sandstones, conglomerates and 
limestones in the southwest and Mid-Transvaal. Here lie the 
auriferous beds. The metal is found in the matrix of the 
conglomerate, but not in the pebbles. The yield is not very 
high, averaging last year thirteen pennyweights per ton of 
sandstone. The beds have been worked to the depth of 1,000 
feet. 2,000 stamps arc already at work crushing four tons a 
day each and obtaining about half an ounce of gold from the 
ton. 
<i. Granites, schists and gneisses of Central Africa, Ma shon- 
aland, Matabeleland, Mozambique, etc. 
The minute geologj" of the gold field is as yet unknown, but, 
as a geological society has already been established at .Johan- 
nesburg with more than 300 members, we may hope soon t<> 
have full details of the structure of the country and the prob- 
able origin of the auriferous sand. 
Great excitement has naturally prevailed in the mining 
stock market in consequence of this unparalleled product of 
gold. Fortunes have changed hands. The English papers 
are full of glowing advertisements of the mines of theWitwa- 
tererand and speculation is rife, as might be expected. Much 
of this is based on "airy nothings" and will collapse, but a 
solid substratum remains, as may be ^'vn from the facts given 
above, and the stability and progress of Johannesburg and its 
gold field are as well assured as were those of California and 
Victoria. e. w. c. 
