Which ore of the following is a mineral of iron ?

Options

A. Pyrolusite
B. Magnetite
C. Malachite
D. Cassiterite

Answer

To determine which ore is a mineral of iron, we will analyze the given options based on their chemical compositions.

### Step-by-Step Solution:

1. **Understand the Definitions**:
- **Ore**: A naturally occurring solid material from which a metal or valuable mineral can be extracted profitably.
- **Mineral**: A naturally occurring inorganic substance with a definite chemical composition.

2. **Identify the Given Options**:
- Pyrolusite
- Magnetite
- Malachite
- Cassiterite

3. **Analyze Each Option**:
- **Pyrolusite (MnO2)**: This is a manganese oxide. It does not contain iron, so it is not a mineral of iron.
- **Magnetite (Fe3O4)**: This is an iron oxide. It contains iron, making it a mineral of iron.
- **Malachite (CuCO3·Cu(OH)2)**: This is a copper carbonate hydroxide. It does not contain iron, so it is not a mineral of iron.
- **Cassiterite (SnO2)**: This is a tin oxide. It does not contain iron, so it is not a mineral of iron.

4. **Conclusion**:
- Among the given options, **Magnetite (Fe3O4)** is the only mineral that contains iron. Therefore, it is the correct answer.

### Final Answer:
**Magnetite is the mineral of iron.**

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