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Encyclopedia of Physical Science and Technology EN014A-653 July 28, 2001 20:55

4 Rare Earth Elements and Materials

TABLE II World Rare Earth Reserves and Reserve Base a,b TABLE III World Mine Production in 1999 a
Lanthanides Yttrium Lanthanides b Yttrium b
Reserve Reserve United States 5,000 —
Reserves c Base c Reserves c Base c Australia — —
United States 13,000,000 14,000,000 120,000 130,000 Brazil 1,400 15
Australia 5,200,000 5,800,000 100,000 110,000 Canada — —
Brazil 280,000 310,000 400 1,500 China 65,000 2,200
Canada 940,000 1,000,000 3,300 4,000 Congo (Kinshasa) — —
China 43,000,000 48,000,000 220,000 240,000 India 2,700 55
Congo — — 570 630 Malaysia 250 7
(Kinshasa) South Africa — —
India 1,100,000 1,300,000 36,000 38,000 Sri Lanka 120 2
Malaysia 30,000 35,000 13,000 21,000 Thailand — —
South Africa 390,000 400,000 4,400 5,000 Former Russia 2,000 125
Sri Lanka 12,000 13,000 240 260 Other countries — —
Thailand — — 600 600 World total (rounded) 76,500 2,400
Former Russia 19,000,000 21,000,000 9,000 10,000
a Modified from Hedrick, J. B. (2000). “U.S. Geolog-
Other countries 21,000,000 21,000,000 — —
ical Survey, Mineral Commodity Summaries,” pp. 135,
World total 100,000,000 110,000,000 510,000 560,000 189.
(rounded) b Metric tons of rare earth oxide. Data may not add to
totals shown because of independent rounding.
a Modified from Hedrick, J. B. (2000). “U.S. Geological Survey,
Mineral Commodity Summaries,” pp. 135, 189,
b Metric tons of rare earth oxide. Data may not add to totals shown 1% level. Monazites are similarly constituted but contain
because of independent rounding. somewhat less La and Ce and greater amounts of elements
c The reserve base includes demonstrated resources that are currently
economic (reserves), marginally economic (marginal reserves), and from Gd to Lu and Y. Xenotime ores contain up to 60%
some of those that are currently subeconomic (subeconomic resources). yttrium with the remainder mostly concentrated in the Gd
to Lu half of the series with relatively little of La, Ce, Nd,
and Pr. This information is summarized in Table IV.
Nei Monggol Autonomous Region) and the United States
deposits (Mountain Pass, CA) are primarily bastnasite.
This latter deposit is of the highest grade yet discovered 3. Abundance of Rare Earths Relative
and is the only one mined principally for its rare earth to Other Elements
content. Most economic monazite and xenotime deposits
Thus La and Ce are the most abundant rare earths while
are in the form of beach sands in which wave action has
Lu and Tm are the most scarce. This leads us finally to the
concentrated the minerals. Such sands contain the Indian
issue of the inappropriate nature of the term “rare earth” to
reserves and most of the remaining world reserves.
describe these elements. In fact, the most abundant “rare
In terms of actual world production of rare earth el-
earth,” Ce, has about the same abundance in the earth’s
ements and the capacity to produce them, the picture
crust as Cu (copper) and is more abundant than B (boron—
changes somewhat as seen in Table III.
a major constituent of all glass), Co (cobalt—a commonly
North America (mostly the United States) with 10%
used alloying agent in steelmaking). Ge (germanium—
of the world reserves accounts for nearly 50% of both
used to make the first transistor), Pb (lead—automobile
production and capacity and Australia with less than 1%
reserves is a strong second. Note that Scandanavia from batteries and gasoline), Sn (tin—as in cans), or U (ura-
whose mineral deposits most of the rare earths were first nium). Even Tm (thulium), the rarest of the rare earths, is
discovered is not presently a major producer. more abundant than Cd (cadmium—a battery component),
I (iodine—from the medicine chest), Hg (mercury—as in
barometers and thermometers), and certainly Ag (silver),
2. Distribution of the Rare Earth Elements
Au (gold), and Pt (platinum).
within the Various Ore Types
Bastnasite ores contain mostly rare earths near the begin-
C. Recovery and Separation of the Rare Earths
ning of the series, La, Ce, Pr, and Nd. For a typical deposit
the figures would be approximately 30% La, 50% Ce, 4% The separation and purification of the rare earths were
Pr, and 15% Nd, leaving the remaining elements at the among the more spectacular chemical accomplishments