92 



UNITED STATES MINERAL RESOURCES 



RESOURCES 



The only resources that have been reasonably well 

 delineated in pegmatites are those in the fine-grained 

 spodumene-bearing pegmatites that are being mined 

 for lithium. These contain a very large amount of 

 beryl ; 800,000 tons has been estimated to be in the 

 pegmatites of North and South Carolina alone. Hovif- 

 ever, because of the low beryl content of the rock 

 (about one-half of 1 percent) and its fine particle 

 size, this beryl will not be economically recoverable. 

 Hence, it is not included in the resource tabulation. 



The coarse zoned pegmatites, on the other hand, 

 contain beryl that is readily recoverable, but the 

 known beryl resources are no more than 10,000 tons, 

 because no exploration is done in advance of mining. 



The larger nonpegmatitic deposits are persistent 

 enough to be explored thoroughly before mining and 

 to yield fairly reliable resource estimates with mini- 

 mal exploration. The three largest districts, Spor 

 Mountain, Utah; Seward Peninsula, Alaska; and 

 Gold Hill, Utah, account for most of the resources 

 of beryllium in known nonpegmatitic deposits as 

 given in table 18. 



Table 18.- 



-Estiviated resources of beryllium, in short tons 

 of metal 



The 60,000 tons of beryllium in nonpegmatitic 

 deposits in the United States are in deposits dis- 

 covered in a period of about 10 years, after which 

 exploration abruptly ceased. Additional deposits 

 doubtless remain to be discovered. These are as- 

 sumed to contain about four times as much beryl- 

 lium as the deposits that are now known. The fol- 

 lowing characteristics of major districts were used 

 in evaluating potential future discoveries: most 

 beryllium districts (1) are associated with high- 

 angle faults of regional extent, generally block 

 faults; (2) are in fluorite metallogenic provinces; 

 and (3) have calcareous rocks as the most favorable 

 host for mineralization. Figure 12 shows areas that 

 are most promising for additional exploration. It 



FiGUEE 12. — Areas of the conterminous United States in which beryllium deposits are most likely to be found. 



