194 



UNITED STATES MINERAL RESOURCES 



trenching and drilling to determine the size of the 

 deposit. Local high-precision surface gravity surveys 

 may be a promising tool for delineating concealed 

 deposits under some circumstances. Because the di- 

 atomite in a deposit may vary considerably, espe- 

 cially from bed to bed, a deposit must be sampled 

 carefully throughout its thickness to determine the 

 quality and potential use of the material. Micro- 

 scopic examination of the rock may be necessary to 

 distinguish diatomite from volcanic ash or from 

 some porcelaneous rocks. 



RESOURCES 



Diatomite resources are difficult to describe be- 

 cause diatomaceous rocks underlie large areas and 

 include strata of various qualities; even the re- 

 sources of California, the principal producing area 

 in the United States, have never been computed 

 and classified according to grade. Hovi^ever, diatom- 

 ite resources of the United States obviously are 

 more than sufficient for many years to come, even 

 allovs'ing for a steady increase in diatomite produc- 

 tion. The abundance of the material is evident, for 

 example, if the deposit controlled by one diatomite- 

 producing company at Lompoc, Calif., is considered. 

 This deposit has been described as covering an area 

 of 3-4 square miles and being workable to a depth 

 of 700 feet (Industrial Minerals, 1969, p. 14), 

 vs^hich suggests that it could supply vi^orld needs for 

 diatomite at the current rate of consumption for 

 several hundred years. On the other hand, factors 

 such as proximity to markets and suitability of the 

 material for specific uses enter into the evaluation 

 of diatomite resources; the location and quality of 

 diatomite deposits seem to be greater factors in the 

 economics of diatomite production than is the 

 amount of material available. 



PROBLEMS FOR RESEARCH 



The areal and geologic occurrences of diatomite 

 generally are w^ell knovi^n, but conditions that aflfect 

 the thickness and quality of deposits are imperfectly 

 understood. Postdepositional circumstances that 

 affect the quality of diatomite also are uncertain. 

 Clearly, geologic vi^ork on diatomite should involve 

 not only the location and classification of deposits, 

 but also should relate the physical features of di- 

 atomite to the geologic history of the rock to aid 

 in the discovery of deposits for particular purposes. 



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