Yes, CHALAZAS is a Scrabble word!

Letter values in Scrabble US: C 3, H 4, A 1, L 1, A 1, Z 10, A 1, S 1.

Is it a valid word?

CHALAZAS is a valid word in the official Scrabble dictionary (US), the UK Scrabble Dictionary and Words with Friends (ENABLE).

basal part of a plant ovule opposite the micropyle; where integument and nucellus are joined
one of two spiral bands of tissue connecting the egg yolk to the enclosing membrane at either end of the shell