tonstein (English, noun)
expansion: tonstein (countable and uncountable, plural tonsteins)
Senses:
topics: geography
geology
natural-sciences
glosses: A hard, compact, kaolinite-rich claystone formed by the diagenetic alteration of volcanic ash, usually occurring as thin, laterally persistent layers interbedded with coal seams.
tags: countable
uncountable
topics: geography
geology
natural-sciences
petrology
glosses: Any indurated argillaceous rock that stands out within coal measures as a distinctive marker horizon.
tags: countable
uncountable
Forms:
form: tonsteins
tags: plural