Name two common varieties of coal.

Explanation

To answer the question about the two common varieties of coal, we can follow these steps:

### Step 1: Understand what coal is
Coal is a fossil fuel that is primarily used as a source of energy. It is formed from the remains of ancient plants and is found in various forms.

### Step 2: Identify the common varieties of coal
There are several varieties of coal, but the most common ones include:
1. **Peat**: This is the initial stage of coal formation and is composed of decomposed plant material. It has a low carbon content and is considered a precursor to coal.
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