The radioactive decay of thallium-206 to lead-206 has a half-life of 4.20 min. Starting with 4.70 x 1022 atoms of thallium-206, calculate the number of such atoms left after 42.0 min.Click to see full answer. In this regard, what is the half life of thallium? 73.1 hours Also Know, what are the uses of thallium? Uses of Thallium Thallium sulfide is used in photocells because its electrical conductivity increases on exposure to infrared light. Thallium oxide is used to make glass that has a high index of refraction. Thallium is also used in gamma radiation detection equipment. Similarly, you may ask, how much does thallium cost? Commercial thallium metal (99%) costs about $40/lb.Where is thallium found?Thallium is found as a mineral in the elements crooksite, lorandite and hutchinsonite. It’s also found as a trace element in iron pyrite and obtained from this ore by roasting the mineral. Small amounts of thallium are found in manganese nodules on the ocean floor.