Refractory (planetary science)

In planetary science, any material that has a relatively high equilibrium condensation temperature is called refractory. ^[1] The opposite of refractory is volatile.

The refractory group includes elements and compounds like metals and silicates (commonly termed rocks) which make up the bulk of the mass of the terrestrial planets and asteroids in the inner belt. A fraction of the mass of other asteroids, giant planets, their moons and trans-Neptunian objects is also made of refractory materials. ^[2]

Classification

The elements can be divided into several categories: ^[1]

Category	Condensation Temperature Range °K	Elements
Super-refractory	∞≥ T ≥ 1700	Re, Os, W, Zr, Hf
Refractory	1700 ≥ T ≥ 1500	Al, Sc, Ca, Ti, Th, Lu, Tb, Dy, Ho, Er, Tm, Ir, Ru, Mo, U, Sm, Nd, La
Moderately refractory	1500 ≥ T ≥ 1300	Nb, Be, V, Ce, Yb, Pt, Fe, Co, Ni, Pd, Mg, Eu, Si, Cr
Moderately volatile	1300 ≥ T ≥ 1100	Au, P, Li, Sr, Mn, Cu, Ba
Volatile	1100 ≥ T ≥ 700	Rb, Cs, K, Ag, Na, B, Ga, Sn, Se, S
Very volatile	700 ≥ T ≥ 0	Zn, Pb, In, Bi, Tl

The condensation temperatures are the temperatures at which 50% of the element will be in the form of a solid (rock) under a pressure of 10⁻⁴ bar. However, slightly different groups and temperature ranges are used sometimes. Refractory material are also often divided into refractory lithophile elements and refractory siderophile elements. ^[3]

References

1. Taylor, Stuart Ross (2001). Solar system evolution: a new perspective : an inquiry into the chemical composition, origin, and evolution of the solar system. Cambridge University Press. pp. 73–75. ISBN   978-0-521-64130-2.
2. Beatty, J. Kelly (1999). Beatty, J. Kelly; Petersen, Carolyn Collins; Chaikin, Andrew (eds.). The new solar system. Cambridge University Press. pp. 314–315. ISBN   978-0-521-64587-4.
3. Davis, Andrew M.; Turekian, Karl K. (2005). Davis, Andrew M.; Holland, Heinrich D.; Turekian, Karl K. (eds.). Meteorites, comets, and planets. Elsevier. pp. 45–47. ISBN   978-0-08-044720-9.