TITANIUM 



663 



offshore titanium placer deposits are large in com- 

 parison with the areas of shoreline placer deposits, 

 and the potential resources therefore are large. If 

 mining of sea-floor manganese nodules becomes a 

 practical source of metals, as suggested by Mero 

 (1965), another source of titanium as a byproduct 

 would be developed. New techniques for economic 

 development of this potential source of metals will 

 determine the possibility of such mining becoming 

 commercial in operation. 



Quantitative estimates of the world's speculative 

 resources of titanium, in terms of contained Ti02, 

 are given below: (Speculative resources are undis- 

 covered mineral deposits, whether of recoverable or 

 subeconomic grade, that may exist in unknown dis- 

 tricts or in unrecognized or unconventional form.) 



Type of deposit Size 



Primary: 



Ilmenite, magnetite, 

 rutile, anatase, 

 brookite, perovskite, 

 and sphene in igneous 

 and metamorphic 

 rocks Large (tens of billions of tons). 



Secondary : 



Unconsolidated placers. 

 Consolidated placers 

 in fairly unmeta- 

 morphosed sedi- 

 mentary rocks i Intermediate (billions of tons). 



Residual: 



Lateritic and saprolitic 

 concentrations in 

 surficial zones Small (hundreds of millions 



Sea-floor nodules: of tons). 



Iron- and manganese- 

 rich nodules con- 

 taining minor amounts 

 of titanium Small. 



EXPLORATION 



Exploration for titanium deposits has been di- 

 rected largely toward the discovery of well-known 

 types of primary deposits, such as the occurrences 

 of ilmenite and titaniferous magnetite in associa- 

 tion with mafic and ultramafic rocks, or toward the 

 discovery of secondary deposits of titaniferous 

 heavy minerals in placers. Background geologic 

 information concerning the occurrence of favorable 

 host rocks or known mineral occurrences is used to 

 provide a basis for selecting target areas for ex- 

 ploration. Because most primary ilmenite deposits 

 contain large amounts of magnetite, these deposits 

 have associated magnetic anomalies. Such anomalies 

 are detected by aeromagnetic surveying, and after 

 anomalous areas are located, they are studied in 

 more detail by ground magnetic surveys, gravity 

 surveys, and detailed geologic mapping. Titaniferous 

 magnetite deposits commonly have somewhat more 



complex magnetic anomalies than those associated 

 with most nontitaniferous magnetitic iron deposits 

 and thus require sophisticated geophysical interpre- 

 tations. High-grade ilmenite deposits have higher 

 densities than their host rocks and are therefore 

 detectable by the gravity anomalies that reflect the 

 diff'erences in density between the ore deposits and 

 their host rocks. Combined magnetic and gravity 

 data interpreted in conjunction with other geologic 

 data are used to pinpoint target areas for drilling 

 and sampling. The sampling and the analyses of 

 the samples provide the basis for evaluation of de- 

 posits that are discovered. 



In exploration for placer deposits, coastal areas, 

 known areas of fossil placers, and terrace deposits 

 along streams are sampled, and heavy-mineral con- 

 centrates from the samples are analyzed to deter- 

 mine their mineral and chemical compositions. 

 Wherever possible, interpretations are made of 

 sedimentary features, such as ancient stream chan- 

 nels, beaches, off'shore bars, and sand dunes. Other 

 sedimentary parameters used are grain size and 

 composition; these make it possible to reconstruct 

 the probable conditions of deposition and concen- 

 tration of heavy minerals and to determine the 

 probable extent of favorable concentrations of the 

 minerals sought. 



Many placer concentrations of heavy minerals 

 contain radioactive minerals. Such deposits can be 

 detected by aerial or ground radiometric surveys, 

 provided that the deposits are not covered by too 

 great a thickness of overburden. Aerial albedo sur- 

 veys will probably be used more in the United States 

 as quantitative albedo measurements become feasi- 

 ble. 



Once the favorable target areas are located, they 

 must be tested by sampling in order to determine 

 the economic potential of the deposits. The samples 

 must be analyzed, and factors such as the quantity 

 and quality of the recoverable ore and the ratio of 

 overburden to ore must be determined. 



PROBLEMS FOR RESEARCH 



The cost of processing the abundant titanium min- 

 eral, ilmenite, to obtain usable titanium dioxide or 

 titanium metal is so much higher than that of proc- 

 essing natural rutile that despite its relative scarcity 

 and higher cost in world markets, rutile is preferred 

 as a source of titanium. So long as rutile is obtain- 

 able from foreign sources at lower cost than that 

 produced in the United States, domestic rutile de- 

 posits of lower grade and higher production cost 

 are noncompetitive. Geologic exploration is needed 

 to find large and higher grade domestic rutile de- 



