Which of the following is not a mineral of iron?

Options

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

Explanation

To determine which of the following options is not a mineral of iron, we will analyze each option provided:

1. **Malachite**:
- Malachite is known as an ore of copper.
- Its chemical formula is Cu2CO3(OH)2, which indicates it contains copper, carbon, and hydroxide ions.
- Therefore, malachite is not a mineral of iron.

2. **Cassiterite**:
- Cassiterite is also known as tin stone and is the primary ore of tin.
- Its chemical formula is SnO2, which shows it is composed of tin and oxygen.
- Thus, cassiterite is not a mineral of iron.

3. **Pyrolusite**:
- Pyrolusite is primarily a manganese mineral and is the main ore of manganese.
- Its formula is MnO2, indicating it contains manganese and oxygen.
- Therefore, pyrolusite is not a mineral of iron.

4. **Magnetite**:
- Magnetite is one of the main iron ores and is indeed a mineral of iron.
- Its chemical formula is Fe3O4, which shows it is composed of iron and oxygen.
- Thus, magnetite is a mineral of iron.

Now, summarizing our findings:
- Malachite, cassiterite, and pyrolusite are not minerals of iron.
- Magnetite is the only mineral listed that is a mineral of iron.

**Conclusion**: The options that are not minerals of iron are malachite, cassiterite, and pyrolusite.

**Final Answer**: Malachite (as it is the first option listed and is an ore of copper).