Show MONAZITE AND ZIRCON minerals containing thorium are in constant demand for use in making incandescent mantles for gas lamps but only one mineral that carries much thorium monazite has thus far been found in quantities large enough to make it commercially valuable some specimens of monazite contain as much as 20 per cent of thorium but the thorium content of commercial monazite which has been washed and otherwise cleaned ranges from 3 to 9 per cent practically all the monazite of commerce is derived from placer or gravel deposits all attempts to extract it from its original rock matrix having failed the deposits are worked like placers by sluicing and hydraulic king and the crude monazite sand obtained is further c on concentrating cent dent rating tables and by electromagnetic electro magnetic machinery which removes its iron content brazil and the united states supply the worlds demand for monazite although the greater part of the output of the united states is used in this country for many years north carolina and south carolina have furnished this supply but important deposits have been lately discovered at several places in idaho monazite in idaho at one of these deposits near center vine ville idaho some trial mining has been done the gravels worked contain both go gold d and mo monazite nazile and the purpose of the 4 experiments has been to devise a method of recovering both samples of the cleaned sand contain nearly 5 per cent of monazite the production of monazite concentrates in the united states in 1909 was pounds valued at an increase of pounds in quantity and of in value over 1908 when tile the production was pounds valued at the output was all obtained from north carolina and south carolina A report on the production of monazite and zircon in 1909 prepared by D B sterrett geologist has just been published 1 shed by the united states geological survey as an advance chapter of the volume mineral resources of the united states ca calendar andar year 1909 11 the report gives statistics of pro production imports and exports and contains a paragraph on the production of zircon A few notes by dr R C wells chemist of the survey on the nieth methods employed by him in making chemical analysis of monazite sands from idaho will be of technical interest the afie report may be obtained w without ith 0 ut charge by applying to the director of the survey at washington |