386 REPORT OF NATIONAL MUSEUM, 1899. 



oughly dried, is further cleaned by pouring from a cup, or a small spout in a bin, 

 in a fine, steady stream from a height of about 4 feet, on a level platform; the lighter 

 quartz and black sand with the fine-grained monazite (tailings) falls on the periphery 

 of the conical pile and is constantly brushed aside with hand brushes; these tailings 

 are afterwards rewashed. Instead of pouring and brushing, the material is sometimes 

 treated in a winnowing machine similar to that used in separating chaff from wheat. 



Although the best grade of sand is as high as 85 per cent pure, its quantitative 

 proportion is small as compared with the second and other inferior grades, and there 

 is always considerable loss of monazite in the various tailings. It is impossible to 

 conduct this washing process without loss of monazite, and equally impossible to 

 make a perfect separation of the garnet, rutile, titanic iron ore, etc. , even in the best 

 grades. The additional cost of such rewashing and rehandling must also be taken 

 into consideration. 



If the material washed contains gold, the same will be collected with the mona- 

 zite in concentrating. It may frequently pay to separate it, which can easily be 

 accomplished by treating the whole mass over again in a riffle box with quicksilver. 



It has been shown that the monazite occurs as an accessory constituent of the 

 country rock, and that the latter is decomposed to considerable depths, sometimes 

 as much as 100 feet. On account of the minute percentage of monazite in the mother 

 rock, it is usually impracticable to economically work the same in place, by such a 

 process as hydraulicking and sluicing, for instance. However, even hillside mining 

 has been resorted to. Such is the case at the Phifer mine, in Cleveland County, 

 North Carolina, 2 miles northeast of Shelby. The country rock is a coarse mica 

 (muscovite and biotite) gneiss, and the small monazite crystals may at times be 

 distinctly seen, unaided by a magnifying glass, in this rock. It is very little decom- 

 posed and still quite hard, and the material that is mined for monazite is the over- 

 lying soil and subsoil, which is from 4 to 6 feet thick. This is loaded on wheel- 

 barrows and transported to the sluice boxes below the water race. The yield is 

 fairly good, and the product very clean, though the cost of working * * * must 

 be considerably iii excess of that of bottom mining. Where the rock contains suf- 

 ficient gold, as it sometimes does, to be operated as a gold mine, there is no reason 

 why the monazite can not be saved as a valuable by-product. 1 



The following localities are represented in the Museum collec- 

 tions: 



Specimen No. 53107, U.S.N.M. Prado, Bahia, Brazil. Monazite-bearing sand from 



the bed of a small stream near the beach. 



Specimen No. 53108, U.S.N.M. Monazite sand, Prado, Bahia, Brazil. Natural con- 

 centrate of beach; represents the condition in which much of the material is 



shipped. 

 Specimen No. 53109, U.S.N.M. -Monazite sand, Prado, Bahia, Brazil. The natural 



concentrate of the beach still further concentrated in the batea. 

 Specimen No. 53110, U.S.N.M. Monazite sandstone, Prado, Bahia, Brazil. A small 



bit of loosely coherent standstone, composed largely of monazite particles. Of 



Quaternary (?) age, and presumably the source of much of the sand on the 



beach. 

 Specimen No. 62568, U.S.N.M. Monazite sand, with magnetic iron and other 



impurities. Henderson County, North Carolina. 

 Specimen No. 63343, U.S.N.M. Monazite sand from near Shelby, Cleveland County, 



North Carolina. 

 Specimen No. 63496, U.S.N.M. Monazite sand, concentrated, from Abbeville, South 



Carolina. 



1 Sixteenth Annual Report U. S. Geological Survey, 1894-95, Pt. 4, pp. 686-687. 



