What is a Mineral?
Minerals are naturally occurring solids. They can be crafted from a single element (such as gold or copper) or from a combination of multiple elements. The earth is made up of thousands of different minerals.
What is the difference between a Mineral and a Rock?
Minerals have a specific chemical structure that is the same throughout all minerals. On the other hand, rocks are composed of many different types of minerals and are not consistent in their structure.
Characteristics of Minerals
Some common characteristics of minerals include:
Solid – All minerals would be solid at normal Earth temperatures.
Naturally occurring – Minerals occur in nature. Solids created in a chemistry lab are not considered minerals.
Inorganic – Minerals that do not come from plants, animals, or other living organisms.
Fixed chemical structure – Specific minerals will always have the same chemical formula. They will have the same combination of elements. Minerals are also often formed with a crystalline structure.
Properties of Minerals
The different minerals are usually identified by the set of properties described below:
Luster – Luster describes how a mineral reflects light. Examples of gloss include glass, metal, shiny, and dull.
Hardness – Hardness describes how easily a mineral’s surface can be scratched. Scientists often use the Moh scale to describe hardness. Using the Moh scale, “1” is the softest mineral and “10” is the hardest. An example of hardness is diamond. Diamond has a hardness of 10 because it is the hardest mineral.
Streak – Streak is the color of the mineral in powder form. One way to determine resistance is to rub the mineral on a hard, rough surface like brick.
Cleavage – Separation describes how a mineral is broken down into pieces. Some minerals break down into small blocks while others can break down into thin sheets.
Specific Gravity (SG) – Specific gravity measures the density of a mineral. It is measured against water where water has a specific gravity of 1. For example, pyrite has a specific gravity of 5 and quartz has a specific gravity of 2.7.
Color – While color is often used to describe a mineral, it is sometimes not the best way to distinguish one mineral from another because one mineral can have many different colors.
Types of Minerals
There are many different types of minerals, but they are generally divided into two groups: silicates and non-silicates. Silicates are minerals that contain silicon and oxygen. More than 90% of the earth’s crust is made up of silicates. The rest of the minerals are grouped into a group called non-silicates.
Some Important Non-silicate Minerals include:
Carbonates – Carbonate contains carbonate (CO3) combined with another element. Calcite is a mineral composed of carbonate and calcium.
Halides – Halides contain a halogen element as the primary element. Table salt (NaCl) is a halogenated mineral made from halogenated chlorine (Cl) and sodium (Na).
Oxides – Oxides are minerals whose main element is oxygen. Chromite is an oxide mineral composed of iron, chromium and oxygen.
Sulfide – Sulfides contain sulfur and one or more metals or semimetals. Pyrite is a sulfide made from iron and sulfur.
Indigenous elements such as copper, gold, diamond, graphite and sulfur can be considered a third group of minerals.
Interesting Facts about Minerals
Scientists who study minerals are called mineralogists.
About 99% of the minerals in the earth’s crust are made up of eight elements including oxygen, silicon, aluminum, iron, calcium, sodium, potassium, and magnesium.
Common minerals include quartz, feldspar, bauxite, cobalt, talc, and pyrite.
Some minerals have streaks of a different color than their body color.
A gem is a rare piece of mineral such as a diamond, emerald or sapphire that is cut and polished to shine.
Certain minerals are needed by our bodies so that we can grow healthy.