The global rare-earth cycle
1995; Elsevier BV; Volume: 225; Issue: 1-2 Linguagem: Inglês
10.1016/0925-8388(94)07134-9
ISSN1873-4669
Autores Tópico(s)Geochemistry and Geologic Mapping
ResumoThe global cycle of rare earths involves a series of complex interactive processes. This dynamic system includes atmospheric phenomena, geologic activity, physical and chemical weathering, hydrologic cycles, and the contributions of mankind. Mankind's effect began with the separation of the first rare earth, 200 years ago. Since that time, demand for the rare earths has continued to increase. Global changes over the past two centuries have been minimal, but measurable. The future effect of increased demand on the global system is not known. On a global scale, a defined base for observation and measurement is necessary to compare and effectively respond to future changes in the system, both natural and those influenced by human activity. The beginning of mankind's effect on the global rare-earth cycle began 200 years ago. Although rare-earth bearing minerals were collected prior to 1794, none were identified as containing a new "rare" and different "earth" (historical term for oxide) until Swedish Lieutenant Karl Axel Arrhenius collected and examined the mineral ytterbite (later renamed gadolinite) in 1787. Separation of the first impure oxide in 1794 by Finnish chemist Johan Gadolin marked mankind's entry into the dynamics of the global cycle as rare earths were extracted from nature and offered to science and industry.
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