TITANIUM 



659 



I 



colored high-grade gneiss (Sheridan and others, 

 1968). These deposits are thought to have been 

 originally laterites or bauxites that contained re- 

 sistant titanium minerals. The rutile forms about 

 2-4 percent of the gneiss. 



SECONDARY RUTILE DEPOSITS 



Secondary deposits of rutile derived from the 

 weathering of primary occurrences of rutile are the 

 most important types of rutile deposits currently 

 mined. These consist mainly of marine placer sands, 

 stream sands and gravels, and lag saprolite deposits. 

 Rutile, having a specific gravity greater than 4.0, is 

 concentrated in placers with other heavy minerals 

 by wave and stream action, in loose sands along 

 coastal areas and along streams. In addition to 

 deposits along modern shores, important quantities 

 of rutile are contained in buried placers in terraces 

 inland from present shorelines. Such deposits com- 

 monly have other valuable heavy minerals such as 

 ilmenite and zircon, and some heavy-mineral depos- 

 its, in which monazite is the most abundant and 

 the most important heavy mineral, also contain 

 significant amounts of rutile. Similar deposits prob- 

 ably occur in oif shore areas near coasts where shore- 

 line rutile deposits indicate availability of suitable 

 types of sediments. Formerly commercial deposits 

 in lag saprolite deposits derived from weathering 

 of titanium-bearing rock are present in Amherst 

 and Nelson Counties, Va. (Fish, 1962; Herz and 

 others, 1970), as well as in Hanover County. The 

 Magnet Cove, Ark., rutile deposits also include some 

 occurrences of the saprolitic type. 



PRIMARY ILMENITE DEPOSITS 



Some of the more important and currently eco- 

 nomic primary ilmenite deposits are in the U.S.S.R., 

 the United States, Canada, and Norway (Lawthers, 

 1957; Peterson, 1966; Rose, 1969; Roy, 1970a). In 

 the Ilmen Mountains (part of the Ural Mountains) 

 of the U.S.S.R. (Lawthers, 1957), large economic 

 deposits of ilmenite and titaniferous magnetite also 

 contain important amounts of vanadium. The 

 titanium-iron ores there measure in the hundreds 

 of millions of tons. Other ilmenite deposits in the 

 U.S.S.R. are known in the Kola Peninsula and in 

 the Ukraine. In the United States, ilmenite-magne- 

 tite deposits in gabbro and anorthosite at Tahawus, 

 Essex County, N. Y. (Peterson, 1966) are a major 

 source of titanium. Economic deposits of ilmenite, 

 hematite, and magnetite occur as segregated masses 

 in gabbro and anorthosite in the Tellnes deposit, 

 Norway, and high-grade ilmenite ores in amphi- 

 bolite at the Otanmaki deposit in Finland (Paak- 



konen, 1956) are mined. Important commercial de- 

 posits of ilmenite, magnetite, and rutile in gabbro- 

 anorthosite are worked in the St. Urbain area, Que- 

 bec, Canada. Large deposits of ilmenite and titani- 

 ferous magnetite in the Bushveld Complex of South 

 Africa are important for their vanadium content. 



SECONDARY ILMENITE DEPOSITS 



Most titanium minerals are relatively resistant 

 to weathering and are commonly found in resistate 

 sediments. Ilmenite forms most of the economic 

 secondary deposits of titanium ; these deposits are 

 placer sands that occur throughout the world. In 

 general, they are in areas peripheral to regions 

 having host rocks containing primary titanium min- 

 eral deposits. During the weathering of ilmenite, 

 iron is released and titanium forms a simple diox- 

 ide, leucoxene, which is commonly present in placers. 

 The placer deposits of ilmenite, rutile, and leucox- 

 ene commonly contain other heavy minerals, such 

 as zircon and monazite, in significant amounts. 



Placer deposits of ilmenite and other titanium 

 minerals occur along present-day beaches where 

 wave action sorts and concentrates the heavy min- 

 erals, and in deltas and along streams where heavy 

 minerals settle from the slower moving water. Fos- 

 sil placers of ilmenite in sedimentary rocks are also 

 known where similar mechanisms in the past have 

 concentrated the heavy minerals. Some placer de- 

 posits have been derived from older detrital depos- 

 its. The coastal areas of all the inhabited continents 

 have significant ilmenite placer deposits. Impoi'tant 

 deposits in the United States are in northern Florida 

 and near Lakehurst, N. J. 



Fossil placer deposits in the United States near 

 Highland and Starke, Fla., are at present being 

 mined for ilmenite, rutile, and zircon, which were 

 originally derived from the crystalline rocks of the 

 Piedmont area (Pirkle and Yoho, 1970). At Lake- 

 hurst, N. J., a fossil placer of ilmenite is being 

 mined from heavy-mineral lenses in sediments of 

 Cretaceous and Tertiary ages. Reworking has con- 

 centrated the heavy minerals into an economic de- 

 posit (Markewicz, 1969). 



Australia is the leading producer of titanium min- 

 erals with a production of 0.98 million tons of il- 

 menite in 1970 (Lynd, 1972) from the coastal sands 

 of Western Australia. Rutile, zircon, monazite, and 

 ilmenite are also recovered from deposits on the 

 coast of Queensland and New South Wales. In 1970, 

 Australia produced 405,735 short tons of rutile, 

 about 89 percent of world production (Lynd, 1972). 

 New Zealand also has large resources of coastal 

 black-sand deposits of ilmenite, which are currently 



