" ▁earth ▁for ▁these ▁elements , ▁with ▁prices ▁to ▁match . ▁ ▁Thor ium ▁content ▁of ▁mon az ite ▁is ▁variable ▁and ▁sometimes ▁can ▁be ▁up ▁to ▁ 2 0 – 3 0 %. ▁Mon az ite ▁from ▁certain ▁carbon at ites ▁or ▁from ▁Boliv ian ▁tin ▁ore ▁ve ins ▁is ▁essentially ▁thor ium - free . ▁However , ▁commercial ▁mon az ite ▁s ands ▁typically ▁contain ▁between ▁ 6 ▁and ▁ 1 2 % ▁thor ium ▁ox ide . ▁ ▁Ac id ▁crack ing ▁ ▁The ▁original ▁process ▁for ▁" c rack ing " ▁mon az ite ▁so ▁as ▁to ▁extract ▁the ▁thor ium ▁and ▁l anth an ide ▁content ▁was ▁to ▁heat ▁it ▁with ▁concentr ated ▁sul fur ic ▁acid ▁to ▁temper atures ▁between ▁ 1 2 0 ▁and ▁ 1 5 0   ° C ▁for ▁several ▁hours . ▁Vari ations ▁in ▁the ▁ratio ▁of ▁acid ▁to ▁ore , ▁the ▁extent ▁of ▁he ating , ▁and ▁the ▁extent ▁to ▁which ▁water ▁was ▁added ▁afterwards ▁led ▁to ▁several ▁different ▁processes ▁to ▁separate ▁thor ium ▁from ▁the ▁l anth an ides . ▁ ▁One ▁of ▁the ▁processes ▁caused ▁the ▁thor ium ▁to ▁precip itate ▁out ▁as ▁a ▁ph osph ate ▁or ▁py roph osph ate ▁in ▁cru de ▁form , ▁leaving ▁a ▁solution ▁of ▁l anth an ide ▁sul f ates , ▁from ▁which ▁the ▁l anth an ides ▁could ▁be ▁easily ▁precip itated ▁as ▁a ▁double ▁sod ium ▁sul f ate . ▁The ▁acid ▁methods ▁led ▁to ▁the ▁generation ▁of ▁considerable