What is a valuable ore of copper, containing copper, iron, and sulphur; -- also called purple copper ore (or erubescite), in allusion to the colors shown upon the slightly tarnished surface called?

bornite — A valuable ore of copper, containing copper, iron, and sulphur; -- also called purple copper ore (or erubescite), in allusion to the colors shown upon the slightly tarnished surface. (Webster's 1913.)

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