Mars

Living off the Mars

The air on Mars consists of 95% carbon dioxide, 3% nitrogen, 1.6% argon, and the remainder is trace amounts of oxygen, water vapor, and other gases.

Its surface is made of a thick layer of oxidized iron dust and rocks of the same color.

Beneath the layer of dust, the Martian crust consists mostly of volcanic basalt rock ( SiO2, K2O + Na2O). The soil of Mars also holds nutrients such as sodium, potassium, chloride and magnesium.

For habitats nitrogen and maybe the Argon from the air being added to Oxygen obtained from the rocks.

Argon is breathable but may build up in the bottom of your lungs (standing on your head will remove it :)