76 
Journal of the Mitchell Society 
[November 
zite they contain. The formations that have been found especi- 
ally favorable for such work are highly pegmatized gneiss or schist. 
Such deposits have generally soon been lost or grown poor, prob- 
ably on account of the fact that the miners have cut through the 
richer bed or failed to follow it in the direction of its extension. 
The occurrence of monazite in saprolite is merely an altered phase 
of the occurrence in hard rock formations. 
COMMERCIAL DEPOSITS 
All the monazite mined in the Carolinas is obtained from gravel 
deposits which lie in and along the stream and creek beds where 
the monazite is collected after being liberated from the rocks by 
their alteration and erosion . While no accurate record has been 
kept of the percentage of monazite in these gravel deposits, yet it 
is undoubtedly true that the percentage per cubic yard, reckoning 
from surface to bed rock, is not over 1 percent. This, however, 
is sufficient to make profitable mining. In many localities it has 
been the custom to sluice not only the gravels but all the over- 
burden, inasmuch as even the top soil carries a small amount of 
monazite. 
There are no large hydraulic plants in operation, but nearly all 
the monazite is obtained in sluice boxes fed by hand. These 
boxes are fitted at their upper end with a sieve or shaking hopper 
with a mesh of about No. 12. The boxes vary in length from 8 
to 20 feet, and in some instances are fitted with riffles holding 
mercury for catching the gold. An interesting fact noted in con- 
nection with the deposition of monazite in the stream beds is that 
when the gravels have been washed for monazite and then left for a 
few months or a year (especially if there has been considerable rainy 
weather), there is another supply of monazite deposited, which in 
many cases can be profitably worked. This monazite has resulted 
from the w T ashing in of the mineral from the surface adjoining the 
streams where it had been during the decomposition and erosion 
of the original rock matrix. This second deposition of monazite 
is facilitated by plowing the adjoining fields. In a few places 
Wilfley tables have been introduced for treating the concentrates 
from the sluice boxes. Where these tables are used the. soil and 
