mineral

definition: 
A substance obtained by mining:A solid, naturally occurring inorganic substance
sentence: 
Three blue-chip companies have also taken a gamble and invested in a total of over eight million acres in the hope of mining platinum and other minerals at some future date.
The solids used include natural clays and minerals, metal oxides and sulfides, metal salts, and mixed metal oxides.
difficulty: 
easy
toefl frequency: 
2
toefl classification: