Yes, STEATITE is a Scrabble word!

Letter values in Scrabble US: S 1, T 1, E 1, A 1, T 1, I 1, T 1, E 1.

Is it a valid word?

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

a soft heavy compact variety of talc having a soapy feel; used to make hearths and tabletops and ornaments

Also: soap-rock.

Not playable in Scrabble US: SOAPROCK.