662 



UNITED STATES MINERAL RESOURCES 



from consideration because of the probable environ- 

 mental damage to scenic and recreational areas that 

 would result from mining. In sparsely inhabited 

 areas, especially in developing nations, such con- 

 siderations may not be deterrents to mining. Politi- 

 cal considerations in the developing nations may 

 temporarily have a great influence on mining 

 activity. 



Placer deposits in some coastal areas are par- 

 tially renewable over periods of years or decades 

 because of continuous reworking of the sands by 

 waves and currents. The grade of the deposits de- 

 creases as the sands are mined repeatedly. 



Deposits such as the titaniferous magnetite 

 bodies and the titaniferous gabbros in the State of 

 New York are irregular in form, and their projec- 

 tion to greater depths or in lateral directions can 

 be done with reasonable certainty only for indi- 

 vidual deposits. They can, however, be considered 

 collectively as being representative of the concen- 

 trations of titanium in their host rocks to a speci- 

 fied depth. Inasmuch as the concentrations of tita- 

 nium in deposits of this type are not related to 

 enrichment relative to the present surface, the quan- 

 tity of titanium in such concentrations for each 

 additional increment of depth should tend to aver- 

 age near the amount that exists in the shallow zone. 

 For example, if nearly 24 million short tons of TiO^ 

 has been identified in the uppermost 500 feet of the 

 districts that have been explored in New York, it 

 is likely that an equivalent amount will exist be- 

 tween depths of 500 and 1,000 feet in these districts. 



Hypothetical resources of titanium in the United 

 States are estimated to be about 155 million short 

 tons TiOi.. This quantity represents only a 53-percent 

 addition to the identified titanium resources, and 

 most of this increase is for primary-type ilmenite 

 deposits. Among these, magnetite-ilmenite deposits 

 of northern New York and eastern Minnesota are 

 high-grade deposits, favorably located with respect 

 to markets. Very large low-grade magnetite-ilmenite 

 deposits in Alaska are distant from markets but are 

 along the coast and are accessible. Primary ilmenite- 

 rutile deposits in Virginia and their associated 

 placer deposits are also favorably located geograph- 

 ically, but competitive land-use considerations could 

 render the placers unavailable. Primary magnetite- 

 ilmenite deposits in Wyoming may contain large 

 hypothetical resources. Placer deposits in Florida, 

 Georgia, South Carolina, North Carolina, and New 

 Jersey contain large tonnages of hypothetical re- 

 sources of titanium. Some of these are also im- 

 portant for monazite, zircon, and other heavy 

 minerals. 



Any attempt to assign quantitative estimates to 

 hypothetical resources of titanium must be made 

 with the recognition that the resource data are in- 

 complete. Hypothetical resources based on modest 

 projections of identified resources and on interpre- 

 tations of the extent of exploration effort and pro- 

 duction records for certain regions are shown in 

 table 144. 



Table 144. — Hypothetical world resources, in millions of 

 short tons, of titanium 



[Hypothetical resources: Undiscovered mineral deposits, whether of re- 

 coverable or subeconomic grade, that are geologically predictable as exist- 

 ing in known districts] 



Continent TiOs 



North America 400 



South America 200 



Australia and New Zealand 100 



Europe 200 



Africa 500 



Asia 200 



Total 1,600 



SPECULATIVE RESOURCES 



Speculative resources of titanium are very great. 

 Ilmenite is a common mineral in mafic and ultra- 

 mafic rocks such as those of the Bushveld Complex 

 of South Africa, in anorthosites of the Canadian 

 Shield, and in similar rocks of Precambrian shield 

 areas of each continent. Many tens of billions of 

 tons of such rocks containing a few percent of 

 ilmenite are within a depth of less than 1 mile be- 

 neath the surface of the earth, and exploration of 

 these great rock units should disclose large bodies 

 having higher than average amounts of ilmenite. 



Bauxite and other lateritic deposits containing 

 aluminum, iron, chromium, cobalt, nickel, and a few 

 percent TiOo are also potential sources of titanium. 

 Lithified placer deposits in sedimentary rocks, such 

 as the extensive black sand deposits in the Upper 

 Cretaceous formations of Wyoming and also pres- 

 ent in Arizona, New Mexico, Utah, Colorado, Idaho, 

 and Montana (Dow and Batty, 1961; Houston and 

 Murphy, 1962), indicate the possibility of signifi- 

 cant resources of titanium minerals in sandstone 

 deposits. Metamorphic equivalents of similar 

 titanium-rich sedimentary rocks and of some mafic 

 plutonic rocks off'er additional possibilities for tita- 

 nium ores. Offshore placer deposits paralleling 

 known coastal placer deposits and placer deposits 

 along coasts where the shallow marine sediments 

 were derived from titaniferous rocks should con- 

 tain concentrations of titanium minerals equivalent 

 to those in shoreline placers or in terrace deposits 

 in raised beaches (McKelvey and Wang, 1969). In 

 many parts of the world the areas favorable for 



