Neon Spaceships could be neutron mining right now. The mined neutrons could be combined with 8 hydrogen Atoms to form 1 Oxygen atom. This could explain the lack of Carbon 14 and the abundance of Oxygen on Earth.
"almost 99% of all carbon atoms are 12C."
https://www.esrl.noaa.gov/gmd/outreach/isotopes/stable.html
How Carbon-14 Dating Works
https://science.howstuffworks.com/environmental/earth/geology/carbon-14.htm
Shows Oxygen is most abundant element in earth's crust.
http://hyperphysics.phy-astr.gsu.edu/hbase/Tables/elabund.html
