Minerals | Solid Chemical Compounds
A mineral is an inorganic solid which has occurred naturally through a geological process. Inorganic means it does not contain any living matter.
Minerals are solid chemical compounds with an internal crystal structure. This means they're made up of crystals. A crystalline solid is a mineral.
A crystal structure is an arrangement of atoms that comes together in a highly ordered, repeating symmetrical pattern. The arrangement forms a crystal lattice. This lattice forms a crystal.
So crystals are composed of an orderly repeating arrangement of atoms. If the atoms do not form in this way the substance will not be crystalline. It can therefore not be a mineral.
Non crystalline or amorphous solids are known as mineraloids. Examples include amber which is fossilised tree resin, a curious material from Russia known as shungite, opal, pearl, moldavite which is a tektite and obsidian which is volcanic glass.
Rocks and minerals are not same. Minerals are made up of crystals, rocks are made up of several different minerals.
Although there are close to 4000 minerals which have been identified, only about 100 are classified as being common. Most rocks are formed from a small number of the most common 'rock-forming' minerals. Some of these include quartz, olivine, calcite and pyroxenes. Peridot is the gemstone variety of olivine, jadeite is a pyroxene.
Identifying some minerals can be very straightforward but others can be extremely difficult. Charoite can often be easily identified on sight alone but apatite is more complex. Throughout history this mineral has been confused for others. In fact the name apatite comes from the Greek words 'deceive' or 'to be misled'.
When identifying a mineral colour is usually a good place to start. It can however also be the most unreliable method because many minerals occur in different colours. Streak and lustre can also help with identification. Streak describes the colour of a mineral in powdered form. It never changes and is not always the same colour as the exterior of the mineral. Lustre describes the way light interacts with the surface of a rock or mineral.
Mohs scale of mineral hardness was created in 1812 as a way of testing scratch resistance of one mineral against another. Diamond which grades 10 is the hardest mineral on the scale, talc at 1 is the softest. Corundum which is 9 can scratch quartz which is 7. Apatite which is 5 can scratch fluorite which is 4. Harder minerals can scratch those which are softer and those of the same hardness can scratch each other. Hardness is not the same as toughness.
Almost everything around us is made up of minerals. The metals in household appliances and cookware, the materials used to produce tableware. Copper used in wiring and pipes is a metallic mineral. Graphite used in pencils is the crystalline form of carbon so it's a mineral. When subjected to high pressure and temperatures graphite transforms into diamond.
Talcum powder, cosmetics, the pigments in paints and even mobile phones and computers are all made from different minerals. The materials used in the production of roads and pavements, soil additives used in agriculture and of course gold, silver and gemstones are all minerals.
When used from a nutritional perspective the word mineral has a slightly different meaning. Minerals are required in small amounts to enable our bodies to function normally. Different amounts are needed by different people depending on age, sex and overall health. Some of the most important minerals for the human body include magnesium, sodium, calcium, potassium, iron, zinc, fluoride, selenium, manganese and chromium to name just a few.