This is an Anthracite Coal Lump. Anthracite can be hard to light initially, but can be used as an extremely powerful heat source once lit. Image Source

This is an Anthracite Coal Lump. Anthracite can be hard to light initially, but can be used as an extremely powerful heat source once lit. Notice it’s dark black color which is the result of its high carbon content. Anthracite is an extremely high grade of coal. Image Source