Tl

a soft grey malleable metallic element that resembles tin but discolors on exposure to air; it is highly toxic and is used in rodent and insect poisons; occurs in zinc blende and some iron ores

スズに似ているが空気に触れると変色する、柔らかく灰色の展性のある金属元素；毒性が非常に強く、殺鼠剤や殺虫剤に用いられる；閃亜鉛鉱や一部の鉄鉱石に含まれる