Compare the chemical formula of magnetite with that of biotite. Why is magnetite mined to obtain iron supplies, but biotite is not?

Magnetite has a chemical formula of: \[Fe_3O_4\] Biotite has a chemical formula of: \(K(Mg,Fe)_3[AlSi_3O_{10}](OH)_2\)

When we compare the chemical formulas of magnetite and biotite: - Magnetite is an iron oxide, containing iron and oxygen atoms in its structure. - Biotite, on the other hand, is a complex silicate, containing potassium, magnesium, iron, aluminum, silicon, and hydroxyl groups in its structure.

Magnetite is the mineral that is preferred for obtaining iron supplies because: 1. It has a higher percentage of iron in its structure (\(Fe_3O_4\) means it has three iron atoms per molecule). 2. The extraction process of iron from magnetite is simpler and less expensive as it involves reducing the iron oxide with carbon, usually in a blast furnace, to obtain iron metal. Biotite, on the other hand, is not preferred for obtaining iron supplies because: 1. It has a lower percentage of iron in its structure (only 1-3 iron atoms in a complex silicate molecule). 2. The extraction process of iron from biotite is more complex and involves various chemical reactions, which makes it more expensive and less attractive for obtaining iron supplies. In conclusion, magnetite is mined for obtaining iron supplies because it has a higher percentage of iron in its structure, and its extraction process is simpler and more cost-effective, compared to biotite.