Thallium - Wikipedia
Although thallium is a modestly abundant element in the Earth's crust, with a concentration estimated to be about 0.7 mg/kg, mostly in association with potassium-based minerals in clays, soils, and granites, thallium is not generally economically recoverable from these sources.Thallous Chloride Tl-201 Injection (Thallous Chloride,,Thallium Tl-201 is cyclotron produced. At the time of calibration it contains no more than 1.0% Thallium Tl-200, no more than 1.0% Thallium Tl-202, no more than 0.25% Lead Pb-203, and no less than 98% Thallium Tl-201 as a percentage of total activity.High thallium concentrations in soils from sites of,,The aim of this study was to assess thallium concentration in topsoil originating from sites of historical mining of Ag, Pb and Zn in western Ma opolska (S Poland). Soil samples were collected from 63 sites, sieved, ground and digested in hot HClO4. Thallium concentration was measured with an atomic absorption spectrometer.