(n.) A rare metallic element of the aluminium group found in some minerals, as certain pyrites, and also in the lead-chamber deposit in the manufacture of sulphuric acid. It is isolated as a heavy, soft, bluish white metal, easily oxidized in moist air, but preserved by keeping under water. Symbol Tl. Atomic weight 203.7.
Webster's Revised Unabridged Dictionary
| APA | Webster's. (2011). thallium. Retrieved September 23, 2026, from http://smartdefine.org/thallium/definitions/2071711 |
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| MLA | Webster's. "thallium" 28 May 2011. Web. 23 September 2026. <http://smartdefine.org/thallium/definitions/2071711> |