Gallium is a chemical element with symbol Ga and atomic number 31. Elemental gallium does not occur in nature, but as the gallium(III) compounds in trace amounts in bauxite and zinc ores. A soft silvery metallic poor metal, elemental gallium is a brittle solid at low temperatures. Held long enough, gallium will melt in the hand as it liquefies at temperature of 29.77 °C (85.59 °F) (slightly above room temperature). Its melting point is used as a temperature reference point. The alloy Galinstan (68.5% Ga, 21.5% In, 10% Sn) has an even lower melting point of −19 °C (−2 °F). From its discovery in 1875 until the semiconductor era, gallium was used primarily as an agent to make low-melting alloys.