The word garnierite is playable in Words With Friends™, no blanks required. Because it is longer than 7 letters, you would have to play off an existing word or do it in several moves.
Words With Friends™ Letter Score: 13
Highest Scoring Words With Friends™ Play In The Letters
Seven Letter Word Alert: (34 words)
angrier, arenite, earring, grainer, granite, grantee, granter, greaten, greater, igniter, inerter, inertia, ingrate, integer, rainier, rangier, reagent, rearing, regrant, regrate, reigner, reinter, retrain, tangier, tarring, tearier, tearing, terrain, terrane, tiering, trainee, trainer, treeing, triaene