Why is chalcocite roasted and not calcined during extraction of copper ?

Explanation

### Step-by-Step Solution:

1. **Understanding the Processes**:
- **Calcination**: This process involves heating carbonate or hydroxide ores to convert them into their respective oxides. It typically occurs in the absence of air and is used for ores like carbonates (e.g., CaCO3 to CaO).
- **Roasting**: This process is used for sulfide ores, where the ore is heated in the presence of oxygen. The sulfide is converted into its oxide, and sulfur dioxide gas is released.

2. **Identifying the Ore**:
- The ore in question is **chalcocite**, which has the chemical formula **Cu2S**. This indicates that it is a **sulfide ore**.
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