Introduction to Minerals
Before learning about the different types of minerals, we will first understand what are minerals. They are formed by geological processes and are usually found inorganic and solid in nature. There are also few organic materials, such as silver, gold, diamond etc they are found in the earth’s crust. Today, there are more than thousands of minerals recognized but only a few of them are common. A mineral is formed through natural processes and it possesses definite chemical composition. We can identify minerals by their characteristic of physical properties such as crystalline structure, hardness, streak, and cleavage. Different gemstones like diamonds, emeralds and sapphires that are produced in industries are identical. Hence they are called man made minerals.
In this article we will explain the classification of minerals, how are minerals classified and the importance of how we classify minerals.
How Many Types of Minerals?
Minerals are mostly classified based on their crystal form Classification of minerals is of two types namely metallic and non-metallic.
[Image will be Uploaded Soon]
1. Metallic Minerals
Metallic minerals have lustre property in their appearance and they consist of metals in their chemical composition. These minerals serve as a potential source of metal and we can extract it through mining. Manganese, iron ore and bauxite are examples of metallic minerals. Metallic minerals can further be divided into two types : ferrous and non-ferrous metallic minerals.
Ferrous minerals mostly contain iron whereas non-ferrous minerals do not contain iron elements.
2. Non-metallic Minerals
Non-metallic minerals are minerals that either show a non-metallic lustre or shine in their appearance. The concentration of available metals is not present in their chemical composition. Limestone, gypsum, and mica are the most common examples of non-metallic minerals.
Bauxite ore mostly exists in deeply weathered rocks. Volcanic rocks contain bauxite deposits in some regions.
Iron metal extracted from iron ore. It never exists in the pure form we have to extract it from iron ore by eliminating the impurities.
Gold is the oldest and most precious element that is known to us.
Manganese ore is a silvery brittle or in the form of grey-white metallic ore that occurs in many forms and we can find it worldwide.
Chemical Composition of Minerals
Nearly about 98.5% of Earth’s crust is made up of only eight elements. These eight elements are oxygen, silicon, aluminium, iron, calcium, sodium, potassium, and magnesium. These are the elements that are made up of most minerals.
All minerals have a specific chemical composition. The silver mineral is made up of only silver atoms and diamond is made only made up of carbon atoms, but most minerals are made up of chemical compounds. Each mineral has its own chemical formula. Quartz is made of two oxygen atoms bonded to a silicon atom, and its formula is SiO2. If a mineral contains any other elements in its crystal structure, then it is not quartz. A hard mineral that has covalently bonded carbon is known as diamond, but a softer mineral that also contains calcium and oxygen along with carbon is known as calcite.
[Image will be Uploaded Soon]
The structure of calcite shows the relationship with calcium (Ca), carbon (C), and oxygen (O) minerals.
Some minerals have a range of chemical composition. Olivine is always made up of silicon and oxygen as well as iron or magnesium or it contains both.
Mineral Classes
Minerals are classified according to their chemical properties. Except for the native class element, the chemical basis for classifying minerals is the anion. It is the negatively charged ion that usually shows up charge at the end of the chemical formula of the mineral. For example, the sulfides are based on the sulfur ion, and it is represented as S2-. Pyrite, for example,FeS2 , is a sulfide mineral. In some cases, the anion is of a mineral class is in the form of polyatomic, such as (CO3)2-, it is the carbonate ion. The major classes of minerals are given below:
silicates
sulfides
carbonates
oxides
halides
sulfates
phosphates
native elements
Silicates
Silicate is a polyatomic anion, (SiO4)4-, which is the tetrahedral shape. Most minerals that are found in the earth’s crust are silicate minerals. All silicate minerals are built of silicon-oxygen tetrahedra (SiO4)4- in different bonding arrangements that form different crystal lattices.
Sulfides
These are based on the sulfide ion, S2-. Various examples include pyrite FeS2, galena PbS, and sphalerite ZnS in its pure zinc form. Some sulfides are mined as sources of metals like zinc, lead, copper, and tin.
Carbonates
These are based on the carbonate ion, (CO3)2-. Calcite, CaCO3, and dolomite are carbonate minerals. Carbonate minerals dissolve relatively easily in water, especially in acid water, and natural rainwater is slightly acid.
Oxides
These are based on the oxygen anion, O2-. Different types of iron oxides include hematite Fe2O3 , magnetite Fe3O4, and pyrolusite MgO.
Halides
Halides have a halogen element present in the anion form, whether it be fluoride F-, chloride Cl-, bromide Br-, iodide I-, or astatide At-. Halite, NaCl, is a halide mineral.
Sulfates
Sulfates have the polyatomic sulfate ion, (SO4)2-, present in the anion form. Anhydrite, CaSO4, is a sulfate.
Phosphates
Phosphates have the polyatomic phosphate ion, (PO4)3-, as the anion. Fluorapatite,Ca5(PO4)3F, which makes our teeth hard, is a phosphate mineral.
Native Elements
These elements are made of only a single element. Gold (Au), native copper (Cu), diamond and graphite are made of carbon, are they all are native element minerals. Therefore, the elements that are purified and crystallized in a laboratory do not qualify as minerals, until and unless they have also been found in nature.
Examples of Minerals
Minerals are solid substances found in nature. They are not alive. The atoms which made up a mineral are fitted together to form a crystal. The chemical composition of these kinds of atoms is in the form of crystals. It is the same for every crystal of that kind although impurities or matter that is not part of the crystal may be included. Gold, diamond, rock salt and graphite is used to make the “lead” of pencils.
A piece of green coloured plastic may look identical to the emerald structure. The Mols hardness test a streak test, colour, luster, cleavage and fracture are all ways of identifying minerals.
Uses of Minerals
Mineral like copper is used in electrical equipment as it is a good conductor of electricity. Clay is used to making cement etc which helps in constructing roads. Fibreglass cleaning agents are made of borax. Given below are the uses of minerals in our everyday life:
Uses of minerals in the body
Uses of metallic minerals
Economic uses of minerals
Various other applications of minerals are used in constructing the building, developing weapons for defence, machinery, making of jewellery, synthesizing fertilizers etc.
Physical Properties of Minerals
Following are the physical properties of minerals:
Colour: It refers to the colour of the mineral.
Streak: It refers to the colour of the mineral’s powder.
Luster: It refers to the way light reflects off the mineral’s surface.
Specific Gravity: It refers to how heavy the mineral is relative to the same volume of water.
Cleavage: It refers to the mineral’s tendency to break along flat surfaces.
Fracture: It refers to the pattern in which a mineral breaks.
Hardness: It refers to what minerals it can scratch and what minerals can scratch it.
Conclusion:
As we have discussed, a substance referred to as a mineral, which is a naturally occurring, inorganic, crystalline solid that has a characteristic chemical composition and crystal structure. The atoms in minerals are arranged in regular, repeating patterns that can be used to identify that particular mineral. It is classified on the basis of their chemical composition, and they are expressed in their physical properties. This module describes the classification of minerals the physical properties that are commonly used to identify minerals. They are colour, crystal form, hardness, density, luster, and cleavage. Also, we know how many types of minerals are there and their characteristics.
FAQs on Types of Minerals
1. What defines a substance as a 'mineral' in Geography?
In Geography, a mineral is defined as a homogenous, naturally occurring substance with a definable internal structure. To be classified as a mineral, it must be an inorganic solid formed through geological processes and possess a specific chemical composition and a distinct crystalline structure.
2. What are the primary types of minerals based on their composition?
Minerals are broadly classified into two main categories based on their chemical composition and properties:
- Metallic Minerals: These minerals contain metal in its raw form. They are good conductors of heat and electricity and have a characteristic lustre or shine. Examples include iron ore, copper, and gold.
- Non-Metallic Minerals: These minerals do not contain metals. They lack the typical properties of metallic minerals, such as lustre and conductivity. Examples include limestone, mica, and potash.
3. How are metallic minerals further categorised?
Metallic minerals are sub-divided into two main groups based on the presence of iron:
- Ferrous Minerals: These are metallic minerals that contain iron. They form the backbone of the metallurgical industry. Important examples include iron ore, manganese, and chromite.
- Non-Ferrous Minerals: These are metallic minerals that do not contain iron. They play a vital role in various industries, from engineering to electronics. Key examples are copper, lead, tin, and bauxite (from which aluminium is extracted).
4. What are some important examples of non-metallic minerals and their uses?
Non-metallic minerals are crucial for many industries. Some important examples include:
- Mica: Known for its excellent insulating properties and ability to withstand high voltage, it is indispensable in the electrical and electronics industries.
- Limestone: Primarily composed of calcium carbonate, it is a basic raw material for the cement industry and is essential for smelting iron ore in a blast furnace.
- Gypsum: Used extensively in the manufacturing of cement and plaster of Paris.
5. Why are minerals so unevenly distributed across different regions?
The uneven distribution of minerals is a direct result of the diverse geological processes that have shaped the Earth's crust. Minerals are formed under specific conditions of temperature and pressure, which vary greatly from one region to another. For instance, some minerals are formed by volcanic activity, while others are created through sedimentation or the immense pressure of metamorphic processes. Because these geological conditions are not uniform globally, mineral deposits are concentrated in specific areas, making their distribution highly uneven.
6. How do geologists identify different types of minerals in the field?
Geologists identify minerals by observing their distinct physical properties. These characteristics are a direct result of the mineral's chemical composition and internal atomic structure. Key identification properties include:
- Hardness: The resistance to being scratched, often tested against a known scale.
- Lustre: The way a mineral reflects light (e.g., metallic, glassy, earthy).
- Colour: The most obvious but often least reliable property.
- Streak: The colour of the mineral's powder when rubbed on a streak plate.
- Cleavage: The tendency of a mineral to break along flat, planar surfaces.
7. What is the fundamental difference between a mineral and a rock?
The key difference lies in their composition. A mineral is a single, naturally occurring inorganic solid with a definite chemical formula and crystalline structure. In contrast, a rock is an aggregate or a mixture of one or more minerals. For example, granite is a rock composed of several different minerals, including quartz, feldspar, and mica.
8. What are 'energy minerals', and why are they classified separately from metallic and non-metallic types?
Energy minerals are resources that are mined or extracted to produce energy and power. They are classified separately because their primary use is as fuel, and most of them have an organic origin, unlike the inorganic nature of most metallic and non-metallic minerals. The main examples of energy minerals are coal, petroleum, and natural gas. They were formed from the fossilised remains of ancient plants and animals over millions of years.
9. How do different modes of occurrence, like veins and lodes, impact the mineral type found?
The mode of occurrence often determines the type of mineral found. Minerals in veins and lodes are found in cracks, faults, or joints of igneous and metamorphic rocks. These are typically smaller occurrences of more valuable metallic minerals like tin, copper, zinc, and lead, which were deposited from hot molten or gaseous solutions. In contrast, minerals in beds or layers, common in sedimentary rocks, are formed by deposition and accumulation. These larger deposits often consist of minerals like coal, gypsum, and salt.
