noun. geological dating that relies on the proportions of radioactive potassium in a rock sample and its decay product, argon.
noun. ['pəˈtæsiːəm'] a light soft silver-white metallic element of the alkali metal group; oxidizes rapidly in air and reacts violently with water; is abundant in nature in combined forms occurring in sea water and in carnallite and kainite and sylvite.
noun. a salt or ester of tartaric acid.
noun. a metallic element having four allotropic forms; used in a wide variety of alloys; found in stibnite.