Lustrous black coal (10)
I believe the answer is:
anthracite
(Other definitions for anthracite that I've seen before include "kind of fuel" , "Hard type of coal" , "High-grade hard coal" , "Hard variety of coal" .)
I believe the answer is:
anthracite
(Other definitions for anthracite that I've seen before include "kind of fuel" , "Hard type of coal" , "High-grade hard coal" , "Hard variety of coal" .)