Mars is made of much the same substances as Earth.
The percentages are different, but Mars has a central core of metallic iron and nickel surrounded by a mantle and crust that consists of silicates, metals, and other components of rocks.
The most abundant elements in the Martian crust are silicon, oxygen, iron, magnesium, aluminum, calcium, and potassium.
The red colour of Mars is caused by the oxidation of iron on its surface.
Less abundant elements are titanium, chromium, manganese, sulfur, phosphorus, sodium, and chlorine .
The atmospheric pressure on Mars is only about 1 kPa.
Its composition is 95.3 %