ABRASIVES 



33 



cations require most of the rest. 



Steel, as shot and grit, is used extensively as a 

 sandblast medium and as pebbles in tumbling mills. 

 More than 200,000 tons is produced for these pur- 

 poses each year. This amount requires the furnace 

 reduction of about 400,000 tons of iron ore. 



Other artificial abrasives are manufactured in 

 relatively small amounts. Many are furnace prod- 

 ucts and are made in much the same manner as 

 aluminum oxide and silicon carbide. Among these 

 are zirconium oxide, cerium and other rare earth 

 oxides, and rouge and crocus (iron oxide for polish- 

 ing). Others are precipitates from aqueous solutions 

 and several of these, including calcium carbonate 

 and silica, duplicte the naturally occurring minerals 

 and are used for the same purposes. 



POTENTIAL RESOURCES 



Resources of the several abrasive materials in the 

 United States range from the infiinitesimal to quan- 

 tities which for practical purposes approach the 

 infinite. There are no knovsm diamond deposits and 

 little prospect of discovering any, but deposits of 

 silica sand are literally underfoot in many parts of 

 the country. The size of deposits of other abrasives 

 lies between these extremes. 



Table 5 gives estimated tonnages for each of the 



Table 5. — Resources, in short tons, of abrasive materials in 

 the United States 



Identified resources ^ 

 Commodity (including reserves =) Hypothetical resources' 



Diamond 



Corundum 125,000 >2,000,000 



Emery 3,000,000 >4,000,000 



Garnet 14,000,000 >100,000,000 



Trlopli (and related 



materials) 4,500,000,000 >10,000,000,000 



Silica sand Large Large 



^Identified resources: specific, identified mineral deposits that may 

 or may not be evaluated as to extent and grade, and whose contained 

 minerals may or may not be profitably recoverable with existing tech- 

 nology and economic conditions. 



-Reserves; identified deposits from which minerals can be extracted 

 profitably with existing technology and under present economic conditions. 



2 Hypothetical resources; undiscovered mineral deposits, whether of 

 recoverable or subeconomic grade, that are geologically predictable as 

 existing in known districts. 



more significant abrasive materials occurring in the 

 United States. Estimates of identified resources are 

 based on the general premise that a tabular deposit. 



one with great length and depth relative to its width, 

 should conservatively produce ore from a volume of 

 rock that is six times the volume of an equidimen- 

 sional quarry opened to the full width of the deposit. 

 Most corundum and garnet and much emery char- 

 acteristically occur as concentrations within lenticu- 

 lar zones in metamorphic rocks having these dimen- 

 sions. Podlike deposits such as those formed mar- 

 ginal to intrusive bodies are estimated to produce 

 ore to a depth equivalent to the longest surface 

 dimension of an individual ore body of average size. 

 Bedded deposits are estimated to produce half as 

 much ore as is indicated by the lateral limits and 

 the average thickness known from extensive out- 

 crop, drill, or mining exploration. 



The apparent large quantities of identified and 

 hypothetical resources of the several abrasive ma- 

 terials relative to their annual consumption makes 

 an estimation of tonnages of speculative resources 

 superfluous. 



SELECTED REFERENCES 



Chandler, H. P., 1960, Tripoli, in Industrial minerals and 

 rocks [3d ed.] : Am. Inst. Mining, Metall., and Petroleum 

 Engineers, p. 881-887. 



Goes, Loring, Jr., 1971, Abrasives: New York, Springer- 

 Verlag, 177 p. 



Cooper, J. D., 1970a, Corundum and emery, in Mineral facts 

 and problems, 1970 ed.: U.S. Bur. Mines Bull. 650, p. 

 939-951. 



1970b, Garnet, in Mineral facts and problems, 1970 



ed.: U.S. Bur. Mines Bull. 650, p. 1001-1011. 



Eardley-Wilmot, V. L., 1928, Diatomite, its occurrence, prep- 

 aration, and uses: Canada Dept. Mines, Pub. 691, 182 p. 



French, A. E., and Eilertsen, N. A., 1968, Abrasives, in 

 Mineral resources of the Appalachian region: U.S. Geol. 

 Survey Prof. Paper 580, p. 261-267. 



Friedman, G. M., 1956, The origin of spinel-emery deposits 

 with particular reference to those of the Cortlandt Com- 

 plex, New York : New York State Mus. Bull. 351, 68 p. 



Ladoo, R. B., 1960, Abrasives, in Industrial minerals and 

 rocks [3d ed.] : Am. Inst. Mining, Metall., and Petroleum 

 Engineers, p. 1-21. 



Larsen, E. S., 1928, A hydrothermal origin of corundum and 

 albitite bodies: Econ. Geology, v. 23, no. 4, p. 398-433. 



Myers, W. M., and Anderson, C. 0., 1925, Garnet, its mining, 

 milling, and utilization: U.S. Bur. Mines Bull. 256, 54 p. 



Pratt, J. H., 1906, Corundum and its occurrence and distribu- 

 tion in the United States (a revised and enlarged edi- 

 tion of Bulletin 180) : US. Geol. Survey Bull. 269, 175 p. 



