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Samarskite Niobate and tantalate of Primary constituent of
  rare earths pegmatite dikes
  Uranium 8-10%

Fergusonite Metaniobate and tantalate " "
  of rare earths
  Uranium 1-6%

Euxenite Niobate and titanate of " "
  rare earths
  Uranium 3-10%

Monazite Phosphate of the rare " "
  earths, chiefly cerium
  Uranium 0·3-0·4%

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