calmstone
Noun
Meaning
calmstone (countable and uncountable, plural calmstones)
(colloquial) A sandstone, shale, or mudstone that forms in layers that are easily split into flagstones.
Noun
calmstone (countable and uncountable, plural calmstones)
(colloquial) A sandstone, shale, or mudstone that forms in layers that are easily split into flagstones.