| Oxygen if the third most abundant element in the universe.[1] The Moon minerals contain plenty of it: The finer regolith, the lunar soil of silicon dioxide glass.[2] Minerals forming the lunar crust are made up of oxygen, silicon, magnesium, iron, calcium, and aluminum, along with small amounts of titanium, uranium, thorium, potassium, and hydrogen.[3] I figure you mean free oxygen or diatomic oxygen O₂, but that stuff is rare in the universe, as it’s quite reactive, and largely irrelevant for asteroid impact chemistry extreme heat and pressure, plenty of oxygen available in the rocks smashing together. 1. https://en.wikipedia.org/wiki/Oxygen 2. https://en.wikipedia.org/wiki/Moon 3. https://science.nasa.gov/moon/composition/ |