, C e ) PO 4 , ▁ ▁mon az ite -( Sm ), ▁( Sm , G d , C e , Th ) PO 4 . ▁ ▁The ▁elements ▁in ▁parentheses ▁are ▁listed ▁in ▁the ▁order ▁of ▁their ▁relative ▁proportion ▁within ▁the ▁min eral : ▁l anth an um ▁is ▁the ▁most ▁common ▁rare - ear th ▁element ▁in ▁mon az ite -( La ), ▁and ▁so ▁forth . ▁Sil ica ▁( Si O 2 ) ▁is ▁present ▁in ▁trace ▁amounts , ▁as ▁well ▁as ▁small ▁amounts ▁of ▁u ran ium ▁and ▁thor ium . ▁Due ▁to ▁the ▁alpha ▁decay ▁of ▁thor ium ▁and ▁u ran ium , ▁mon az ite ▁contains ▁a ▁significant ▁amount ▁of ▁hel ium , ▁which ▁can ▁be ▁extracted ▁by ▁he ating . ▁ ▁Mon az ite ▁is ▁an ▁important ▁ore ▁for ▁thor ium , ▁l anth an um , ▁and ▁cer ium . ▁ ▁It ▁is ▁often ▁found ▁in ▁pla cer ▁depos its . ▁India , ▁Mad agas car , ▁and ▁South ▁Africa ▁have ▁large ▁depos its ▁of ▁mon az ite ▁s ands . ▁The ▁depos its ▁in ▁India ▁are ▁particularly ▁rich ▁in ▁mon az ite . ▁ ▁Mon az ite ▁is ▁radio active ▁due ▁to ▁the ▁presence ▁of ▁thor ium ▁and , ▁less ▁commonly , ▁u ran ium . ▁The ▁radi ogen ic ▁decay ▁of ▁u ran ium ▁and ▁thor ium ▁to ▁lead ▁enables ▁mon az ite ▁to ▁be ▁dated ▁through ▁mon az ite ▁ge och ron ology . ▁Mon az ite ▁cry st als