Which one of the following varieties of coal is considered the best quality ?

Coal is classified into four main varieties based on its carbon content and heating value: peat, lignite, bituminous, and anthracite. Anthracite is considered the highest quality and highest rank of coal [3]. It is a hard coal characterized by a very high carbon content, typically ranging from 80% to 97%, and contains the lowest levels of moisture and volatile matter [4][t1]. Due to its high carbon density, it provides the highest energy output and heating value among all coal types [t1][t10]. In contrast, peat represents the initial stage of coal formation with high moisture, while lignite (brown coal) and bituminous (soft coal) represent intermediate stages with lower carbon concentrations [c1][c2]. Anthracite is rare, expensive, and burns with a short blue flame, making it highly desirable for industrial and metallurgical purposes [c4][t3].

Sources

1. [1] Environment and Ecology, Majid Hussain (Access publishing 3rd ed.) > Chapter 9: Distribution of World Natural Resources > coal as a Resource > p. 9
2. [3] Geography of India ,Majid Husain, (McGrawHill 9th ed.) > Chapter 8: Energy Resources > Classification > p. 2
3. [4] https://www.eia.gov/energyexplained/coal/