(a) Baryte, (b) Galena, (c ) Zine blende and (d) Copper pyrites. How many of these minerals are sulphide based?

Explanation

To determine how many of the given minerals are sulfide-based, we need to analyze each mineral's chemical formula and identify if it contains the sulfide ion (S²⁻).

1. **Baryte (BaSO₄)**:
- Baryte is composed of barium sulfate. The formula indicates that it contains the sulfate ion (SO₄²⁻) instead of the sulfide ion (S²⁻).
- **Conclusion**: Baryte is **not** sulfide-based.

2. **Galena (PbS)**:
- Galena is composed of lead sulfide. The formula shows that it contains the sulfide ion (S²⁻).
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