Is “Clast” a Scrabble word?
Yes
CLAST
Valid in at least one Scrabble dictionary
Valid in these dictionaries
SOWPODS / CSW
Scrabble UK & International
TWL / NWL
Scrabble North America
Large English Dictionary
General English word list
Meaning of Clast
/klæst/
noun
1.A fragment of rock that was broken from a larger rock or rock unit.