Thank you for visiting nature.com. You are using a browser version with limited support for CSS. To obtain
the best experience, we recommend you use a more up to date browser (or turn off compatibility mode in
Internet Explorer). In the meantime, to ensure continued support, we are displaying the site without styles
and JavaScript.
Covariant figure of deviation value of La–ash index in the C2 coal seam. The deviation value of La refers to Table 4, and the ash index refers to Table 3.
