Mineral Bearing Oxides
Oxides are found at the surface in the upper layer of the earth. Minerals usually occur in lesser amounts in igneous and metamorphic rocks and also as preceding grains in sedimentary rocks. Minerals are found in this upper layer, although they are very small and the correct equipment is needed to mine them. These minerals are both hard, and soft.
Unlike the minerals of the sulfide class, which exhibit ionic, covalent, and metallic bonding, oxide minerals generally display strong ionic bonding. They are relatively hard, dense, and refractory.
The monetary value of several oxides is fairly high, including the main ores of iron (hematite and magnetite), chromium (chromite), manganese (pyrolusite, as well as the hydroxides, manganite and romanechite), tin (cassiterite), and uranium (uraninite)
Fun fact: Mars gets its red colour from the iron oxide in its soil, which has the same consistency of talcum powder.