Yes, KAOLINS is a Scrabble word!

Letter values in Scrabble US: K 5, A 1, O 1, L 1, I 1, N 1, S 1.

Is it a valid word?

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

a fine usually white clay formed by the weathering of aluminous minerals (as feldspar); used in ceramics and as an absorbent and as a filler (e.g., in paper)

Also: china clay, china stone, porcelain clay, terra alba.