What is the soil on Mars?

Answer 1

Mars has a variety of minerals in the topsoil called regolith; iron-rich smectite clays, magnesium sulfate, iron oxides, and reactive oxidizing agents of unknown chemistry. They detected no organic compounds. Spectral analysis of the dust storms identified the smectite clay as montmorillonite. Smectites have the property of expanding when they contact water, and contracting when they dry. Silicate minerals, oxides (mostly iron), and some calcium carbonate were also found.

Mars soil composition has 5-14 % iron oxide. It is rich in iron, covered with rust thus making it red. The most prevalent elements in the soil patch were silicon and iron. It also found significant levels of chlorine and sulfur.Mineral called olivine was also found.

Source(s):

http://www.jpl.NASA.gov/releases/2004/25…

http://www.anu.edu.au/Physics/nineplanet…

However, where terrestrial soild contains a lot of carbon compounds, these are almost unknown on Mars. And Mars' red color comes from a compound unknown on Earth--Fe2O7--now called a super oxide of iron. It is unstable in earthly conditions and can't exist here. Other than that, Mars has silicates of various sorts, and soil clearly derived from grinding down of basalt and other lavas.