Yes, CARNAUBA is a Scrabble word!

Letter values in Scrabble US: C 3, A 1, R 1, N 1, A 1, U 1, B 3, A 1.

Is it a valid word?

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

hard yellowish to brownish wax from leaves of the carnauba palm used especially in floor waxes and polishes
Brazilian fan palm having an edible root; source of a useful leaf fiber and a brittle yellowish wax

Also: carnauba wax, carnauba palm, wax palm, copernicia prunifera, copernicia cerifera.