Introduction:
A mineral is a naturally occurring inorganic substance that has a definite chemical composition and physical properties. It is characterized by its orderly atomic structure and is usually composed of one or more elements. However, the statement that is NOT true about a mineral is option D, which states that a mineral is composed of at least two elements.

Explanation:
Naturally occurring organic and inorganic substance:
- A mineral is a naturally occurring substance that is found in the Earth's crust. It can be either organic or inorganic.
- Organic minerals are those that contain carbon and are derived from living organisms, such as coal or diamond.
- Inorganic minerals, on the other hand, do not contain carbon and are formed through geological processes, such as the crystallization of magma or the precipitation of minerals from water.

Orderly atomic structure:
- One of the key characteristics of a mineral is its orderly atomic structure.
- The atoms within a mineral are arranged in a specific and repetitive pattern, resulting in a crystal lattice.
- This arrangement gives minerals their distinct physical properties, such as hardness, cleavage, and crystal shape.

Definite chemical composition and physical properties:
- Another important characteristic of a mineral is its definite chemical composition.
- Each mineral has a specific chemical formula that describes the elements present and their proportions.
- For example, quartz is composed of silicon and oxygen in a 1:2 ratio, giving it the chemical formula SiO2.
- Minerals also have specific physical properties, such as color, luster, density, and streak, which can be used to identify and distinguish them from one another.

Composed of at least two elements:
- The statement that a mineral is composed of at least two elements is not true.
- While some minerals do contain more than one element, such as feldspar (which contains aluminum, silicon, and oxygen), there are also many minerals that consist of just one element.
- Examples of minerals composed of a single element include gold, silver, sulfur, and diamond.
- These minerals have a definite chemical composition, but they consist of only one type of atom.

Conclusion:
In conclusion, a mineral is a naturally occurring inorganic substance that has an orderly atomic structure, a definite chemical composition, and specific physical properties. The statement that is NOT true about a mineral is that it is composed of at least two elements. While some minerals do contain more than one element, there are also many minerals that consist of only one element.

D is incorrect