Using research by Wood (2019), any of the elements with a relatively high condensation temperatureThe condensation temperature is the temperature at which 50% of the element would be condensed (in the form of a solid) from a gas of solar composition at a total pressure of 10 bar. of 1291 K < TC,50 < 1806 K in the solar nebulaThe primitive gas and dust cloud around the Sun from which planetary materials formed.1. They are the first elements to condense out of a cooling gas. Refractory elements are the main building blocks of rocky planets, dwarf planets and moons, inner belt asteroids and a portion of other icy moons, outer-belt asteroids, gaseous planets and trans-neptunian objects2.
For more information, visit the page on the Condensation Temperatures of the Elements (Volatile & Refractory).