Ore, Mineral
noun
A mineral stone is an ore / mineral.
こうせき
This is a jukugo word, which usually means on'yomi readings from the kanji. If you know the readings of the kanji, you'll know how to read this as well.
どんな鉱石でも、彼が触ると金に変わってしまうのさ。
Every mineral he touches turns to gold.