# Does Xenon really covalently bond to oxygen within quartz?

Wikipedia's Xenon; occurrence and production says

Within the Solar System, the nucleon fraction of xenon is $$\small\mathsf{1.56 \times 10^{-8}}$$, for an abundance of approximately one part in 630 thousand of the total mass. Xenon is relatively rare in the Sun's atmosphere, on Earth, and in asteroids and comets. The abundance of xenon in the atmosphere of planet Jupiter is unusually high, about 2.6 times that of the Sun. This abundance remains unexplained, but may have been caused by an early and rapid buildup of planetesimals—small, subplanetary bodies—before the heating of the presolar disk. (Otherwise, xenon would not have been trapped in the planetesimal ices.) The problem of the low terrestrial xenon may be explained by covalent bonding of xenon to oxygen within quartz, reducing the outgassing of xenon into the atmosphere.

I know that crystals can provide unusual amounts of local pressure. For example, this answer explains that ice VII has been discovered at room temperature as inclusions in diamonds.

Question: But I'm still surprised to read about covalent bonding of xenon with oxygen within quartz. How/where has this been observed in naturally occurring mineral or rock, and what is the evidence of covalent bonding?

• This may have some helpful information but it's paywalled so I won't be able to read it for the next few days: Retention of Xenon in Quartz and Earth's Missing Xenon science.sciencemag.org/content/310/5751/1174 – uhoh Mar 5 '19 at 6:53

Not sure this is appropriate for Earth Science SE (Chemistry SE would be a better fit), but the answer is "maybe". quoting from the same Wikipedia article:

Three oxides of xenon are known: xenon trioxide ($$\small\mathsf{XeO_3)}$$ and xenon tetroxide $$\small\mathsf{(XeO_4)}$$, both of which are dangerously explosive and powerful oxidizing agents, and xenon dioxide $$\small\mathsf{(XeO_2)}$$, which was reported in 2011 with a coordination number of four.[97] $$\small\mathsf{XeO_2}$$ forms when xenon tetrafluoride is poured over ice. Its crystal structure may allow it to replace silicon in silicate minerals.[98] The $$\small\mathsf{XeOO^+}$$ cation has been identified by infrared spectroscopy in solid argon.[99]

Cited references

97. Bell, C.F. (2013). Syntheses and Physical Studies of Inorganic Compounds. Elsevier Science. p. 143. ISBN 9781483280608.

98. Cockett, A.H.; Smith, K.C.; Bartlett, N. (2013). The Chemistry of the Monatomic Gases: Pergamon Texts in Inorganic Chemistry. Elsevier Science. p. 292. ISBN 9781483157368.

99. Brock, D.S.; Schrobilgen, G.J. (2011). "Synthesis of the missing oxide of xenon, XeO2, and its implications for earth's missing xenon". Journal of the American Chemical Society. 133 (16): 6265–9. doi:10.1021/ja110618g. PMID 21341650.

Evidence is given in Crepisson et al (2019) for xenon (as $$\small\mathsf{XeO_2}$$) incorporation into silica at high pressure. XRD measurements show changes in the lattice consistent with xenon substituting for silicon in the oxide structure.

• Can you find specific answers to "How/where has this been observed, and what is the evidence of covalent bonding?" I'd assumed that "quarts" refers to a mineral, not simply the chemical SiO2. Am I wrong? – uhoh Mar 5 '19 at 3:23
• Quartz. Wikipedia does give a reference [98] in the article to the possible presence of Xe in silicate structures, so I would look that up. – Oscar Lanzi Mar 5 '19 at 3:24
• I may ask a chemistry question later, but right now I'm asking about xenon being bonded to oxygen within terrestrial quarts minerals. Maybe "go look that up" is not the best response? – uhoh Mar 5 '19 at 3:30
• This is a really interesting experimental study showing that Xe can be in quartz, but there's the question of whether this actually occurs in nature. – Gimelist Mar 6 '19 at 21:43
• I've added a bounty; if you have a chance to add anything there it would be great! – uhoh Dec 11 '19 at 10:36