Gallium highly reactive (rubidium and caesium) nor highly toxic (mercury) and can therefore be used in metal-in-glass high-temperature thermometers. It is also notable for having one of the largest liquid ranges for a metal, and for having (unlike mercury) a low vapor pressure at high temperatures. Gallium's boiling point, 2673 K, is more than eight times higher than its melting point on the absolute scale, the greatest ratio between melting point and boiling point of any element. Unlike mercury, liquid gallium metal wets glass and skin, along with most other materials (with the exceptions of quartz, graphite, and Teflon), making it
Cadmium telluride photovoltaics in Mexico and Sweden. In 1984 astrophysicists identified tellurium as the universe's most abundant element having an atomic number over 40. Certain undersea ridges are rich in tellurium. The manufacture of a CdTe cell includes a thin coating with cadmium chloride () to increase the cell's overall efficiency. Cadmium chloride is toxic, relatively expensive and highly soluble in water, posing a potential environmental threat during manufacture. In 2014 research discovered that abundant and harmless magnesium chloride () performs as well as cadmium chloride. This research may lead to cheaper and safer CdTe cells. By themselves, cadmium and tellurium are toxic