Bismuth is a silvery-white metallic element with a pinkish tint on freshly-broken surfaces. It is rarely found in nature in its elemental form. Bismuth forms beautifully colored and geometrically intricate hopper crystals, shown in the image to the left, as it slowly cools and solidifies from its molten state. Among the heavy metals, it is the heaviest and the only non-toxic.  Bismuth has been used in solders, a variety of other alloys, metallurgical additives, medications, and in atomic research. Bismuth was long thought to be a variety of lead or tin, which it resembles, until the chemist Claude Geoffroy showed in 1753 that it is a separate element. In the early 1990's, research began on the evaluation of bismuth as a nontoxic replacement for lead in such uses as ceramic glazes, fishing sinkers, food processing equipment, free-machining brasses for plumbing applications, lubricating greases, and shot for waterfowl hunting.