Witherite: Gemstones Information

Witherite is BaCO3 and forms translucent to transparent grey or white, yellow- or brown-tinged botryoidal to spherical fibrous or granular masses of the orthorhombic system with hardness 3.5 and SG 4.24–4.29. The RI for the alpha, beta and gamma rays is 1.529,1.676 and 1.677, biaxial negative with birefringence 0.148.SG 4.24–4.29. The RI for the alpha, beta and gamma rays is 1.529,1.676 and 1.677, biaxial negative with birefringence 0.148. Witherite may show a green or yellow fluorescence with phosphorescence under SWUV. Witherite occurs in hydrothermal veins as a low-tem- perature mineral, good examples from Alston Moor, Cumbria,England; large yellow crystals from mines in the Rosiclare area,Hardin County, Illinois, USA. Crystals are pseudohexagonal dipyramidal due to repeated twinning.