Killas

Killas is a Cornish mining term for metamorphic rock strata of sedimentary origin which were altered by heat from the intruded granites in the English counties of Devon and Cornwall. The term is used in both counties. ==Origin== The deposition of the killas strata occurred during the Devonian and Carboniferous geological periods. The sediments are...
Found on http://en.wikipedia.org/wiki/Killas

killas

clay slate
Found on http://phrontistery.info/k.html
No exact match found