Which of the following is a carbonate ore?

Options

A. pyrolusite
B. malachite
C. diaspore
D. cassiterite.

Explanation

To determine which of the given options is a carbonate ore, we will analyze each option one by one.

### Step 1: Analyze Pyrolusite
- **Description**: Pyrolusite is primarily an ore of manganese.
- **Chemical Formula**: The formula for pyrolusite is MnO2.
- **Type of Ore**: Since it contains manganese and is an oxide (not a carbonate), it is not a carbonate ore.

### Step 2: Analyze Malachite
- **Description**: Malachite is known as a copper carbonate hydroxide.
- **Chemical Formula**: The formula for malachite is Cu2CO3(OH)2.
- **Type of Ore**: As it contains carbonate (CO3) in its structure, malachite is indeed a carbonate ore.

### Step 3: Analyze Diaspore
- **Description**: Diaspore is an ore of aluminum.
- **Chemical Formula**: The formula for diaspore is Al2O3·H2O.
- **Type of Ore**: This compound is a hydrated aluminum oxide and does not contain carbonate, making it not a carbonate ore.

### Step 4: Analyze Cassiterite
- **Description**: Cassiterite is an ore of tin.
- **Chemical Formula**: The formula for cassiterite is SnO2.
- **Type of Ore**: Since it is an oxide of tin, cassiterite is also not a carbonate ore.

### Conclusion
After analyzing all the options, the only carbonate ore among the given choices is **malachite**.

### Final Answer
The carbonate ore is **malachite**.

---