Yes, TELLURIUMS is a Scrabble word!

Letter values in Scrabble US: T 1, E 1, L 1, L 1, U 1, R 1, I 1, U 1, M 3, S 1.

Is it a valid word?

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

a brittle silver-white metalloid element that is related to selenium and sulfur; it is used in alloys and as a semiconductor; occurs mainly as tellurides in ores of copper and nickel and silver and gold

Also: atomic number 52.

Not playable in Scrabble US: TE.