Light rare earth elements composition

Nd + Cr — Ca - - TF. Similar model was also proposed for titanite enriched by light rare-earth elements (up to 3.5 wt.%). It was concluded that the following mechanism of substitution consistent with compositional data [LREEf+ + [Fe +] - Ca + + Ti +. 

Figure 10.6. Observed secular trends in the chemical composition of sedimentary rocks. Eu/Eu = ratio of observed normalized Eu concentration to that predicted (Eu ) from extrapolation between REE Gd and Sm. REE = rare earth element LREE = light REE HREE = heavy REE. Data from several authors as presented in Veizer (1988).

An interesting stage in the development of primer mixes was the use of pyrophoric metal alloys, first patented in 1936 and improved in 1964. These rare earth alloys, as used in cigarette lighter flints, give a shower of sparks when lightly scraped. A typical pyrophoric alloy is misch metal, which has the following approximate composition cerium 50%, lanthanum 40%, other rare earth elements 3%, and iron 7%. 

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