rockfoil

NOUN
8 LETTERS · STARTS WITH R

rockfoil is a valid 8-letter word worth 17 points in Scrabble and 19 points in Words with Friends.

SCRABBLE WORDS WITH FRIENDS
R1O1C3K5F4O1I1L1
1 + 1 + 3 + 5 + 4 + 1 + 1 + 1 =17 PTS
DOUBLE WORD → 34TRIPLE WORD → 51
MEANING

What does rockfoil mean?