What is the definition of a mineral?

A mineral is defined as a natural, inorganic substance that has a specific chemical composition and usually possesses a characteristic crystalline structure. This definition highlights several key characteristics that minerals must have: they must occur naturally (not produced by human activity), be inorganic (not formed from living organisms), and have a definite chemical formula which establishes the proportions of the elements present. Additionally, minerals typically exhibit an ordered internal structure, which results in the geometric shapes we recognize in crystals.

The other options describe substances that do not fit this definition. For example, synthetic substances, while they may mimic the properties of minerals, are not naturally occurring. Organic compounds are derived from living organisms and do not qualify as minerals due to their organic nature. Lastly, a mixture of different elements without a specific structure does not meet the criteria of having a defined chemical composition or an ordered structure, which are essential for something to be classified as a mineral. Thus, the first choice aligns perfectly with the established scientific definition of a mineral.