Hematite

Hematite is a common Resource in Astroneer. It is mined from reddish-black deposits and can be refined in the Smelting Furnace to produce Iron.

Tundra is the easiest planet to find Hematite on.

Source
Hematite can generally be found on the surface or in caves of the following planets:

Media
Hematite Hématite Гематит