Mineral :

noun (from “mine”) - A constituent element of rock in major, accessory, or trace amounts. A rock may consist of one or several mineral species.
At the microscopic scale, a mineral is composed of atoms or groups of atoms arranged either regularly or irregularly in the three dimensions of space. A mineral is therefore defined by a chemical formula (e.g., Quartz = SiO₂) and a crystalline structure (e.g., Pyrite = cubic). (adapted from Foucault & Raoult, 2010; Michel, 2016; and Hochleitner, 2018).

adj. - Opposed to organic matter, meaning different from the material that supports life and is composed of complex carbon chains. (adapted from Foucault & Raoult, 2010, and Michel, 2016)

To identify a mineral, it is necessary to observe and/or measure its physical properties. There is a wide range of tools and methods designed to assess these properties. Among them:

Minerals can occur in many, sometimes surprising, forms. Most mineral species can exhibit different shapes depending on their crystallization conditions. However, these shapes are always dependent on the crystal system.

Some minerals have characteristic colors, while others can display a wide variety of them.

This refers to a mineral’s ability to transmit or reflect light. A mineral can be:

• Transparent (lets light pass through)
• Translucent (lets some light through)
• Opaque (does not let light through)

Luster is the way a mineral reflects light. The name of the luster often resembles a familiar material: vitreous (glassy), metallic, greasy, etc.

Fracture describes how a mineral breaks when it does not follow its natural planes of cleavage.

Streak is the color observed (or not) when the mineral is rubbed against a white surface like a porcelain plate. Unlike external color, the streak is usually consistent for a given mineral species.

Hardness is a mineral’s ability to scratch another. It is measured using the Mohs scale, ranging from 1 (softest) to 10 (hardest).
Note: Hardness is not to be confused with toughness. For example, diamond is very fragile but has a hardness of 10.

Density is calculated as the ratio of the mass of a sample to the mass of an equal volume of water.
A mineral’s relative density can also be estimated by hand-weighing, although this method is much less precise.

Magnetism is the mineral’s ability to be influenced by a magnetic field. Some minerals, such as magnetite and hematite, can be attracted to a magnet.

Radioactivity is the mineral’s ability to emit radioactive radiation. It is measured using devices such as a Geiger counter.
Radioactivity can be strong in mineral species that contain elements like radon or uranium.

The asbestos group includes various fibrous minerals used in industry for their physico-chemical properties (resistance to high temperatures, non-combustibility, electrical/mechanical/chemical resistance, absorbency, flexibility, etc.).
Unfortunately, some of these properties are also harmful to the environment and human health.

Fluorescence is a mineral’s ability to emit electromagnetic radiation almost instantly in response to exposure to electromagnetic radiation of a shorter wavelength, such as ultraviolet light.