Molybdenite in the context of Molybdenum

Anhydrite, or anhydrous calcium sulfate, is a mineral with the chemical formula CaSO₄. It is in the orthorhombic crystal system, with three directions of perfect cleavage parallel to the three planes of symmetry. It is not isomorphous with the orthorhombic barium (baryte) and strontium (celestine) sulfates, as might be expected from the chemical formulas. Distinctly developed crystals are somewhat rare, the mineral usually presenting the form of cleavage masses. The Mohs hardness is 3.5, and the specific gravity is 2.9. The color is white, sometimes greyish, bluish, or purple. On the best developed of the three cleavages, the lustre is pearly; on other surfaces it is glassy. When exposed to water, anhydrite readily transforms to the more commonly occurring gypsum, (CaSO₄·2H₂O) by the absorption of water. This transformation is reversible, with gypsum or calcium sulfate hemihydrate forming anhydrite by heating to around 200 °C (400 °F) under normal atmospheric conditions. Anhydrite is commonly associated with calcite, halite, and sulfides such as galena, chalcopyrite, molybdenite, and pyrite in vein deposits.

Hübnerite or hubnerite is a mineral consisting of manganese tungsten oxide (chemical formula MnWO₄). It is the manganese endmember of the manganese–iron wolframite solid solution series. It forms reddish brown to black monoclinic prismatic submetallic crystals. The crystals are typically flattened and occur with fine striations. It has a high specific gravity of 7.15 and a Mohs hardness of 4.5. It is transparent to translucent with perfect cleavage. Refractive index values are n_α = 2.170 – 2.200, n_β = 2.220, and n_γ = 2.300 – 2.320.

Typical occurrence is in association with high-temperature hydrothermal vein deposits and altered granites with greisen, granite pegmatites and in alluvial deposits. It occurs associated with cassiterite, arsenopyrite, molybdenite, tourmaline, topaz, rhodochrosite and fluorite.

Molybdenum disulfide (or moly) is an inorganic compound composed of molybdenum and sulfur. Its chemical formula is MoS₂.

The compound is classified as a transition metal dichalcogenide. It is a silvery black solid that occurs as the mineral molybdenite, the principal ore for molybdenum. MoS₂ is relatively unreactive. It is unaffected by dilute acids and oxygen. In appearance and feel, molybdenum disulfide is similar to graphite. It is widely used as a dry lubricant because of its low friction and robustness. Bulk MoS₂ is a diamagnetic, indirect bandgap semiconductor similar to silicon, with a bandgap of 1.23 eV.