any of the more than 100 known substances (of which 92 occur naturally) that cannot be separated into simpler substances and that singly or in combination constitute all matter

a silvery ductile metallic element found primarily in bauxite

a trivalent metalloid element; occurs both in a hard black crystal and in the form of a yellow or brown powder

a rare silvery (usually trivalent) metallic element; brittle at low temperatures but liquid above room temperature; occurs in trace amounts in bauxite and zinc ores

a rare soft silvery metallic element; occurs in small quantities in sphalerite

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