Define the term used in metallurgy.
Gangue

Explanation

**Step-by-Step Solution:**

1. **Understanding Metallurgy**: Metallurgy is the branch of science and engineering that deals with the extraction of metals from their ores and the preparation of these metals for use.

2. **Definition of Ore**: Ores are naturally occurring solid materials from which a metal or valuable mineral can be extracted profitably.

3. **Extraction Process**: During the extraction of metals from ores, it is important to note that ores often contain impurities along with the desired metal.

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