48 KIvISHA MITCHELI^ SCIENTIFIC SOCIETY. 



as much as 100 feet. On account of the minute per- 

 centag^e of monazite in the mother rock, it is usually 

 impracticable to economically work the same in place, 

 by such a process of hydraulickin^- and sluicing" for 

 instance. 



However, hillside miningf of surface soil to depths of 

 4 to 6 feet, has been carried on in certain localities 

 with apparent success. The material is transported 

 in wheelbarrows to washing* boxes situated below a 

 water race, as shown in the accompanying- illustration 

 from the Pheifer mine, three miles east of Shelby. The 

 resulting monazite product is very clean, and the cost 

 of digging and washing the soil is even less, at times, 

 than that in working the lowland gravels. 



The value of monazite is more or less dependent on 

 the percentage of thorium which it contains, as this is 

 the element of greatest value in the manufacture of 

 the incandescent mantles. As the percentage of thoria 

 varies in difierent sands, the value of the sand conse- 

 quentl}^ varies in a measure also. There is no method 

 of determining even the probable percentage of thoria, 

 excepting by careful chemical analysis. Some mona- 

 zite contains practically no thoria. The best Carolina 

 sand runs from 2 to as high as 6 per cent, thoria. 



The price of Carolina monazite has varied from 25 

 cents per pound in 1887, to as low as 3 cents for infe- 

 rior grades and 6 to 10 cents for the best grades in 

 1894 and 1895. 



The production and value of Carolina sand for the 

 past three years was as follows: 



