Yes, ERYTHRITE is a Scrabble word!

Letter values in Scrabble US: E 1, R 1, Y 4, T 1, H 4, R 1, I 1, T 1, E 1.

Is it a valid word?

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

a reddish mineral consisting of hydrated cobalt arsenate in monoclinic crystalline form and used in coloring glass; usually found in veins bearing cobalt and arsenic

Also: cobalt bloom.