BY STEVE VOYNICK
ROCK SCIENCE
Of the 42 minerals that contain molybdenum as an essential element, most collectors are familiar only with wulfenite and molybdenite. Wulfenite (lead molybdate, PbMoO4) crystallizes in the tetragonal system as thin tabs with a diagnostic, bright-orange color. Molybdenite (molybdenum disulfide, MoS2), the only ore of molybdenum, crystallizes in the hexagonal system as opaque, distorted tabs and dark-bluish-gray masses with a metallic luster and a telltale greasy feel.