When sedimentary host rock is heated as a result of coal seam fires, the host rock is pyro-metamorphosed (high temperature/ low pressure) resulting in the formation of paralava, a low-grade metamorphic rock formed adjacent to coal seams. This paper describes an outcrop locality of clinker (paralava) in the Upper Cretaceous Blackhawk Formation within the Book Cliffs coalfields of central Utah, which formed as the result of a coal seam fire.
Eves, Robert L. and Davis, Larry E.
"Coal Clinker Site in the Late Cretaceous Blackhawk Formation, Castle Gate, Utah, USA,"
The Compass: Earth Science Journal of Sigma Gamma Epsilon:
4, Article 2.
Available at: http://digitalcommons.csbsju.edu/compass/vol87/iss4/2