2. Maturity of coal

A coal company has found a thick horizon of anthracite. The company wants to estimate the maturity of the coal in more detail.

2a. How would you expect the chemical composition to vary in general from less to more mature coal?

2b. The company wants to combine chemical investigations with an independent method to get more reliable results on the maturity of the anthracite. Suggest an alternative method and explain how it works.