What is Witherite?
Witherite is a dense barium carbonate found in hydrothermal lead-zinc veins and valued for pale crystals, botryoidal surfaces and high specific gravity.
Mineralogy and structure
Reference formula: BaCO3. Witherite is orthorhombic with the ideal formula BaCO3. COD 1000033 provides an exact structural reference. Barium carbonate is toxic if ingested, so the specimen should be labelled and handled responsibly. Witherite is classified with carbonates and has orthorhombic crystal symmetry. Typical hardness is 3–3.5 on the Mohs scale and specific gravity is approximately 4.2–4.4.
Colour, lustre and habit
Typical colours include colourless, white, cream, yellowish, grey. The usual prismatic, botryoidal, granular habit and vitreous, pearly, resinous lustre help describe a specimen, but colour alone is not diagnostic.
Formation and notable localities
Witherite forms in or is associated with low-temperature hydrothermal veins, baryte-bearing lead-zinc deposits and carbonate-rich cavities. Important documented localities include Northern England, Germany, Romania, Poland, the United States and China.
A heavy pale carbonate from a classic ore vein
Witherite combines a soft pale appearance with unexpectedly high density, making it memorable in the cabinet. Classic English specimens and botryoidal form are especially desirable.
Collecting and care
Do not ingest, grind or acid-test; keep away from children, food and dust, and clean gently without soaking.
