WITHERITE BaCO3 (orthorhombic) . Crystals form as twinned prismatic,pseudohexagonal or dipyramids . Cave-in-Rock, Hardin County, Illinois . 毒重石 為相當罕見礦物，晶体看似許多錐面体所推積而成塔狀物． 表面有明顯橫紋，硬度 3 - 3.5，在長．短波紫外燈照射下顯現淡藍色彩．有毒，可作為殺鼠藥！ 紫色的礦物為螢石．著名產地∼Cave-in-rock, Rosiclare, Illinois, USA; Alston Moor, Cumberland and Durham, England; Thunder Bay area, Ontario, Canada and Germany.
礦名來源：Named after the English natural historian, W. Withering (1741-1799).

經典名礦欣賞 ．２．３．４．５．６
NO.86