Mineral

Table of Contents

Mineral Definition

A mineral (min·er·al, ˈmɪn.əɹ.əl) refers to any of the various naturally-occurring abiogenic substances, usually in distinct crystalline form and of definite chemical composition, and many of which are essential to organisms as a nutrient.

noun, plural: minerals
Etymology: Medieval Latin minerale, from minera (“ore”)
Variant: minerall (obsolete)

Overview

A substance pertains to that which has a definite chemical composition and distinct properties. It is made up of elements in combination with another or the same elements. Hence, all compounds are considered substances but not all substances are compounds as pure elements are also chemical substances. In the same way, minerals are substances but not all substances are minerals. Most minerals are compounds made up of more than one element. Nevertheless, allotropes of an element may also be considered minerals. In fact, they are sometimes referred to as pure minerals. An allotrope of an element pertains to any of the multiple substances formed by only one type of element although these substances could differ in structure. For instance, allotropes of carbon include coal, graphite, and diamonds. They are made up of only one type of element — carbon. A pure mineral would be a type of mineral made up of elements in uncombined form but with a distinct mineral structure. Examples of pure minerals are gold, silver, platinum, copper, and iron.
In the next section, some of the fundamental characteristics of a mineral are briefly discussed.

Characteristics of Minerals

To be considered a mineral, the substance must occur in nature. It means it is not artificially made. A diamond is a mineral and the hardest one there is. However, synthetic diamonds cannot be considered a mineral in this case. A mineral is one that is formed by a natural geologic process.

Minerals are abiogenic, meaning it is not produced by the activity of living organisms. A pearl is naturally occurring and a gemstone but is not regarded as a true mineral. Shelled mollusks produce pearls within their soft tissues (called the mantle). Nevertheless, a natural (wild) pearl is made up of layer upon layer of nacre and sometimes with calcite. Nacre, in turn, is a composite material made from the organic conchiolin protein and aragonite (calcium carbonate). Thus, a pearl is not a mineral per se but a material that contains substances typified as minerals (such as calcite and aragonite) but is not a mineral itself.

The same principle applies to the likes of amber, jet, bone, tooth, shells, urinary calculi, oxalate crystals in plants, and hard fossilized remains. Some fossils are considered minerals when a formerly living organism left an impression on mud, for instance, that eventually was filled with mineral sediments that replaced the decayed body part. In this regard, minerals are described as inorganic, which, in this case, means that it is not derived from or produced by organic living things but by a geologic process. Thus, by being inorganic, it does not necessarily mean that it would not contain carbon. In fact, the Nickel-Strunz classification sets a class of minerals that includes all organic minerals. They contain organic carbon and are not produced biologically, but rather of geologic origin.

Minerals are in crystalline form. Their atoms are arranged in an orderly pattern that repeats at regular intervals. As such, they may be represented with a chemical formula. They display distinctive properties such as density, luster, hardness, and cleavage that can be used to distinguish one mineral from the other. They are stable and solid at room temperature. One of the exceptions is mineral water (H₂O) which is liquid at room temperature but crystalizes as ice below 0 °C.

Biological Importance

Several minerals are vital to organisms. They serve as a dietary source of important nutrients. In the context of nutrition, the definition of a mineral is less restrictive. A mineral pertains to any inorganic element that is essential to nutrition. Minerals are one of the four groups of essential nutrients; the others are vitamins, essential fatty acids, and essential amino acids.

In humans, the essential elements are (1) bulk elements, (2) macrominerals, and (3) trace elements (or trace minerals).

The bulk elements, which comprise the bulk of the human diet, are carbon, hydrogen, oxygen, and nitrogen. Other references include nitrogen and sulfur in this group. The recommended human dietary consumption of these nutrients is ten grams per day.¹
The macrominerals, which are essential as well but in relatively lower amounts than the bulk elements, are calcium, phosphorus, potassium, sodium, chlorine, and magnesium. These nutrients provide essential ions and act as key components of biological compounds, e.g. DNA and RNA.
A trace element is a chemical element required for survival but needed in very small quantities. Examples of trace elements are iron, silicon, zinc, rubidium, copper, strontium, bromine, tin, manganese, iodine, aluminum, lead, barium, molybdenum, boron, arsenic, cobalt, chromium, nickel, selenium, lithium, and vanadium.¹ Iron, for instance, is a component of hemoglobin. This biomolecule occurs in the red blood cells in humans and other vertebrates. The iron component of hemoglobin binds to oxygen in respiratory organs to be transported throughout the body. Apart from oxygen, hemoglobin can also bind to and carry the waste product, i.e. carbon dioxide, from tissues.

Biominerals

Biomineralization is the process of producing a so-called biomineral. A biomineral refers to (purportedly) a mineral produced by the activity of living things. These minerals are not true minerals though, as already explained above (see section: “Characteristics of minerals”). Biominerals are produced by living organisms often for mechanical or structural support to existing tissues. Tissues that contain biominerals are called mineralized tissues. Some examples of mineralized tissues are bones, cartilages, tooth enamel and dentin, shells of mollusks, and diatoms. Examples of biominerals are silicates, carbonates, and calcium phosphates. Other examples are gold and iron deposits by certain bacteria.

References

Essential Elements for Life. (2012, January 1). Retrieved from ://2012books.lardbucket.org/books/principles-of-general-chemistry-v1.0/s05-08-essential-elements-for-life.html Link