Here's why:

* Hard and Burns Hot: Anthracite is the highest grade of coal, meaning it has undergone the most intense heat and pressure during its formation. This results in a very dense, hard coal that burns with a high heat and produces very little smoke.

* Metamorphic Origin: Anthracite is a metamorphic rock, meaning it formed from existing rock (in this case, coal) that was transformed by heat and pressure.

Let me know if you'd like to know more about anthracite!