coronium

[kuh-roh-nee-uh m]

noun Astronomy.

a hypothetical element once thought to exist because certain spectral lines in the emission spectrum of the solar corona could not be identified by known elements. These lines were subsequently found to be emitted by certain highly ionized metals.

Origin of coronium

First recorded in 1885–90; coron(a) + -ium

Dictionary.com Unabridged Based on the Random House Unabridged Dictionary, © Random House, Inc. 2018

This unknown element has received for the time being the name of "Coronium."
Astronomy of To-day
Cecil G. Dolmage
And the extreme strength of the lux metal fiber made it stronger, pound for pound, than steel or coronium.
Islands of Space
John W Campbell
At the supper table Wade and Arcot reported to the others the curious constants they had discovered for coronium.
The Black Star Passes
John W Campbell
I took a coronium hack saw that will eat through molybdenum steel like so much cheese, and it just wore its teeth off.
The Black Star Passes
John W Campbell
The name “coronium” has therefore been given to the supposed gas which forms it.
Encyclopaedia Britannica, 11th Edition, Volume 8, Slice 10
Various