/ Dictionary / Index L light mineral: Meaning and Definition of Find definitions for: light' min"eral Pronunciation: [key] — Geol. Geol. any rock-forming mineral that has a specific gravity of less than 2.8 and is generally light in color. Cf. dark mineral. Random House Unabridged Dictionary, Copyright © 1997, by Random House, Inc., on Infoplease. light-minded light mineral oil Related Content Daily Word Quiz: cygnet Analogy of the Day: Today’s Analogy Spelling Bee: Today’s Spelling Bee Frequently Misspelled Words Frequently Mispronounced Words Easily Confused Words Writing & Language