How do crystals form?
Crystals can be naturally-occurring precious gems like quartz or everyday substances like sugar and salt crystals or snowflakes. They can also be artificial, like synthetic diamonds. Crystals can be used decoratively in our food, making analog watches tick!
The process of liquid cooling into a solid crystal is called crystallization. This mostly happens underground in volcanic fissures. Magma (liquid rock) cools and solidifies with similar molecules gathering together and creating an angular shape.
These bonded ions tend towards regularity and stability as it’s easier to form into. Their shape is known as a polyhedron, a three-dimensional polygon with flat faces, straight edges, and sharp corners. This is a self-organizing system that defies entropy.
The final crystal lattice can be affected by the minerals involved, the temperature, the pressure, and the rate of cooling. Sometimes they also form from mineral deposits as water evaporates, like natural salt.
You can have liquid crystals – as used in LCD screens. Glass is a supercooled amorphous liquid that isn’t crystalline, while crystal glassware with lead content is more costly but not crystal in structure!
Is a crystal a type of rock?
Crystals are made of minerals, and rocks are also made from minerals or sediments, but they are different. All crystals are minerals, but not all minerals are crystals. Minerals have a crystalline atomic structure.
Meanwhile, rocks are composites of minerals with a less uniform structure. Rocks aren’t clear like many crystals – although you can find crystals formed within igneous rocks, such as a vein of quartz. Stones and pebbles are just smaller pieces of rock.
In jewelry, crystals and colored stones are referred to as precious or gemstones. A gem is a rare mineral with a pure formation, but not necessarily the regular faces of a crystal – such as amber or opal. Crystals are generally defined by their shape.
The study of these is called gemology and crystallography – but you probably guessed that! This comes under geology in science. Some people believe that certain crystals and gems are lucky or have healing qualities – this kind of alternative medicine unproven by scientific evidence, dating back to Ancient Greek.
What kinds of crystals are there?
The chemical bonds of crystals can be metallic, ionic, covalent, van der Waals, and others. As a result, you can get the following shapes of crystal lattices:
Triclinic, monoclinic, orthorhombic, tetragonal, trigonal, hexagonal, and cubic.
They call have sparkling flat faces and a symmetrical atomic arrangement, but these names refer to their structure and how made sides they have. If every atom is in a perfect, repeating pattern, they are an ‘ideal’ crystal, but many have crystallographic defects or impurities.
Some of the common crystals you can find are:
- Quartz (sometimes used to keep time)
A rare kind of crystal is a diamond made of compressed carbon. Manufacturing synthetic diamonds are very useful as they are one of the hardest substances on Earth and are needed for many applications. However, as they are uncommon and difficult to mine, retailers of engagement rings drove the price and demand.
The unethical practice of extracting these precious crystals in wartorn African countries led to them being known as ‘blood diamonds’ or ‘conflict diamonds.’ This came to international attention in the late nineties.