Yes, EPITAXIES is a Scrabble word!

Letter values in Scrabble US: E 1, P 3, I 1, T 1, A 1, X 8, I 1, E 1, S 1.

Is it a valid word?

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

growing a crystal layer of one mineral on the crystal base of another mineral in such a manner that its crystalline orientation is the same as that of the substrate