Crystals have always fascinated human beings, their clarity and nearly perfect symmetry captivating our attention since the earliest times. The word crystal is derived from the Ancient Greek word krustallos, from kruos meaning ‘ice cold’. It was originally thought that crystals were a type of ice that was so cold it would never melt. In fact, crystals are minerals in which the atoms are arranged in regular geometrical patterns. Just as our DNA determines the colour of our hair and our growth patterns, the shape of a crystal is the expression of its internal atomic structure.
Most of the Earth’s crystals were formed millions of years ago as the molten rock cooled and hardened to form the Earth’s crust. By volume and weight the largest concentrations of crystals in the Earth are part of the Earth’s solid bedrock. Other crystals have been created as the lava from volcanic eruptions cools down. The slower the molten rock cools, the larger the crystals that are formed. Other types of crystal are created slowly over time as liquids underground find their way into cracks and deposit minerals. Temperature, pressure, chemical conditions and the amount of space available are some of the factors that affect a crystal’s growth. Sometimes crystals develop in confined spaces and in this case they form crystalline masses but may not grow into their typical crystal shape.
Crystals are mainly formed from silicon and oxygen, silicon being a most prolific element in the Earth’s core. When silicon and oxygen combine, they form silicon dioxide, which is also known as quartz. The other elements which are present during this process are what create the myriad of different types of crystals and contribute to their properties. There are several other major crystal components, including carbon from which diamonds are formed.
The shape (or lattice) of a crystal falls into one of seven basic structures. Cubic crystals, for instance, are based on a square inner structure; examples include fluorite, garnet and pyrite. The shapes of tetragonal crystals are all based on a rectangular inner structure, and include four-sided prisms and pyramids, trapezohedrons and eight-sided and double pyramids. Stunning natural crystal forms include clusters, points and crystal caves; however, crystals are also often cut and polished into specific shapes such as spheres, hearts or figurines.
One of the most striking features of crystals is their colour. When we see colour we are actually seeing the wavelengths of light that are reflected rather than absorbed by an object. Clear crystals such as clear quartz take in and then reflect out light without changing it, hence they are colourless. Other crystals, such as peridot, are nearly always the same colour because certain light-absorbing atoms are an essential element of the mineral’s atomic structure. Yet other crystals, such as amethyst, can come in a range of different colours. In this case it is light-absorbing impurities in the atomic structure that produce the colour. These may be present in greater or smaller quantities creating, for instance, the different shades of amethyst.
Crystals are actually all around us, an essential component of many modern items that we take for granted. Computers, phones, radios and watches, traffic lights and even space shuttles all rely on the capacity
of certain crystals to generate electrical impulses when mechanically stressed or to resonate when an electrical charge is applied. The beauty and energy of crystals have delighted and inspired us for millennia. When we pick up a crystal that we are drawn to we are connecting with one of the Earth’s ancient treasures. Little wonder that we often feel it is a storehouse of wisdom and a potent source of energy.