▁active ▁mer cur y ▁mine ▁in ▁the ▁United ▁States ▁before ▁it ▁shut ▁down ▁in ▁ 1 9 9 2 . ▁ ▁U ran ium ▁was ▁discovered ▁in ▁the ▁cal der a ▁in ▁ 1 9 5 3 , ▁and ▁it ▁was ▁extracted ▁mainly ▁at ▁the ▁Moon light ▁mine ▁on ▁the ▁cal der a ' s ▁south western ▁edge , ▁from ▁a ▁r hy ol ite ▁bre c ci ated ▁fault ▁zone . ▁The ▁u ran ium ▁ore ▁min er als ▁include ▁u ran in ite ▁and ▁coff in ite . ▁The ▁age ▁of ▁the ▁u ran ium ▁formation ▁is ▁assumed ▁to ▁be ▁the ▁same ▁as ▁the ▁cal der a ▁t uff , ▁which ▁is ▁approximately ▁ 1 6 . 1 ▁Ma . ▁Other ▁depos its ▁in ▁the ▁cal der a ▁contain ▁or es ▁of ▁ant im ony , ▁ces ium , ▁and ▁l ith ium . ▁ ▁The ▁Th acker ▁Pass ▁l ith ium ▁depos it , ▁located ▁within ▁the ▁cal der a , ▁is ▁a ▁prospect ▁that ▁in ▁ 2 0 1 7 ▁was ▁said ▁to ▁be ▁the ▁most ▁significant ▁l ith ium - cl ay ▁resource ▁in ▁the ▁U . S . ▁ ▁References ▁ ▁Category : Land forms ▁of ▁Har ney ▁County , ▁Oregon ▁Category : Land forms ▁of ▁H umb old t ▁County , ▁Nev ada ▁Category : Land forms ▁of ▁Mal he ur ▁County , ▁Oregon ▁Category : Land forms ▁of ▁the ▁Great ▁Bas in ▁Category : Cal der as ▁of ▁the ▁United ▁States ▁Category : Vol cano