Rubedo

"A jagged crytalline [sic] ore. Gives off radiant energy."

- In-Game Description

Rubedo is an uncommon component that can be found on Earth and Pluto regions. It is usually found in quantities of 10 to 30.

Earth Major looting locations include Oro, Pacific, and Gaia. They drop in the normal quantities. The infected maps seem to be best for farming as the vast amount of enemies thrown at you can be killed and farmed for rubedo along with the chests around the map.