The Fascinating World of Minerals

Mineral basics

Definition:

The definition of a mineral has several parts:

1. It must be naturally occurring.  Crystals produced in laboratory (synthetic) are not, strictly speaking, minerals.



2. It must be inorganic, meaning that it is not the product of a biological process.



3. It must be a crystalline solid.  A mineral is a single, solid substance (phase) which cannot physically be separated into simpler compounds. Rocks are usually aggregates of minerals that can be physically separated from one another.



4. It must have a definite chemical composition that can be represented by a chemical formula (e.g., SiO₂). But this composition is not necessarily fixed, olivine, for example, may vary in composition from Mg₂SiO₄ to Fe₂SiO₄.  However, the chemical variation occurs between strict limits and any given composition has a specific formula (e.g., Mg_1.8 Fe₂SiO₄).

From this definition, you can see that mineralogy relates chemistry and physics to geologic materials through these tree sub-disciplines:

Why study minerals?

As we said previously, rocks are aggregates of minerals.  Therefore, studying minerals is essential in understanding how the earth and other planets formed and evolved.

Also, some minerals have economical value (e.g. gold, cupper, nickel, diamond etc.).  Understanding how those minerals form will help exploration geologists find them.