Flint clay is a claystone composed of microcrystalline to cryptocrystalline kaolinite or halloysite; it is smooth, hard, flint-like in appearance, and breaks with a conchoidal fracture.

A flint clay parting in the Fire Clay coal of the Breathitt Formation (Middle Pennsylvanian, estphalian B) occurs throughout most of eastern Kentucky and in parts of Tennessee, Virginia, and West Virginia.

Examination of Westphalian continental reconstructions, trade wind patterns, and a present-day, ash-fall distribution indicate that the location of the volcanic source for this flint clay was along a line from Kentucky to North Carolina (approximately due east). The intersection of this line with a palinspastically replaced, known Hercynian magmatic arc occurs in extreme eastern North Carolina. This is the approximate location of the volcanic source for the ash.

Because of the extensive distribution of the parting, the Fire Clay coal bed is the only coal bed in eastern Kentucky that can be positively identified over a large area.

Mining Method: Underground/ room and pillar.

Production Equipment: Continuous miner units.