Class : Carbonates, nitrates, borates
    Subclass : Anhydrous carbonates
    Crystal system : Orthorhombic
    Chemistry : BaCO₃
    Rarity : Rare to very rare

Witherite is a rare barium mineral, known only from a few localities in the world. Its structure is identical to that of aragonite although the Ba - Ca substitution is very limited in natural samples. It can transform into baryte. Witherite is a hydrothermal mineral constituting part of the matrix of rare low-temperature fluorite-baryte veins. It was named in honor of the English physicist and mineralogist William Withering who described the mineral. Witherite forms prismatic crystals always twinned in pseudohexagonal assemblages. Parallel groupings are common, giving fibroradiated aspects to the crystal masses. Witherite also forms white crusts with a vitreous luster often associated with barite, as well as botryoidal or globular masses. Its color is grayish white with often a yellow or greenish gray hue. It is distinguished from barite by its fluorescence and phosphorescence under UV light. It is an occasional ore of barium.

Main photo : Witherite from Nentsberry Haggs Mine, England © Rock Currier

Willemite twins are rare, but known on {10-10}.

No fakes listed for this mineral species.