What must I do to help my mother to capitalize on mineral rights (coal) that she inherited from her father?

My grandfather purchased mineral rights to 81 acres of land in a coal-mining area in 1944. Those rights ped to his heirs (my mother) who is wondering what to do. I suggested that with oil so expensive, now might be a good time to mine the coal. How do we exercise the "mineral rights" on property that we don't own? Are 81 acres of coal enough to outweigh the costs of mining and transporting the coal to market? The deed "grants unto my grandfather and his heirs all the coal within or underlying that certain tract of land ... together with al mining rails, mine cars, mine fan and mine scales upon the above described premise. Together with the right to mine and remove all the coal there under without liability for damages for injury to the surface together with all privileges and right of ways necessary for the convenient mining and transport of the same … To have and to hold the said coal … to the only proper use, benefit and behoof of the said party, his heirs and igns forever."