Welcome to another in a series of posts about crystals with this post being about crystal structure. Of course, the dazzling thing about crystals is their spectacular sparkles. And, they have dazzled us throughout all the ages.
Do you know that the ancient Greeks gave the name “krystallos” to the rock they thought was frozen so hard it could never melt? That was the name they attributed to “quartz”. In fact, the name “crystal” derives from the Greek word “krystallos”. Interestingly, that myth about “frozen and can’t melt” in regard to quartz was only dispelled in the 18th century.
Crystals have been defined by scientists throughout history. Some of the definitions have been remarkably close to what is known today. I say “remarkably” because they had no instrumentation as we do today to take such measurements.
The delightful thing is, all crystalline materials have one thing in common. That is an internal structure of regularly repeating three-dimensional patterns. In addition, every crystalline from any source, even the most irregular or misshapen shares this atomical crystal structure.
The Right Conditions for Crystal Structure
As we’ve said in previous posts, the absolute right conditions have to be in place for any type of crystal to form. In addition to that, it takes the right combination of ingredients although the variety is endless, for the crystal to form in just the right conditions and environment.
All these factors such as the crystal’s external shape and growth are a result of the available chemical ingredients, the prevailing conditions, and how the atoms link together. The variety of shapes that might come from that process include form cubes, needles, fibers, plates, or masses.
Although theoretically, there are 230 different three-dimensional crystal lattices that can form in nature, there are actually only 14 different, regularly ordered patterns in which crystals grow. These are the “space lattices” and are seen in diagrams as “balls and spokes”. To clarify, the balls represent the atoms and the spokes represent the ionic bonds that hold them together.
Self-Replication of Crystal Structure
Crystals self-replicate as their external layer provides an atomic template for the next stage of growth. Then, it continues to add layers that match the original layer all the while being affected by the conditions of growth in their environment.
Crystal lattices first separate into seven crystal systems. Then, those systems are further separated into 32 classes of crystals. This is also the number of different combinations of centers, places, and axes of symmetry possible.
To learn the class of a crystal, first, imagine a line going through the center. A “plane of symmetry” divides an object in half so that the two halves are mirror images of each other. On the other hand, an “axis of symmetry” is how many times the crystal appears to be the same when it rotates 360 degrees.
For example, a two-fold axis of symmetry is repeated every 180 degrees, while a three-fold repeats every 120 degrees.
The Seven Crystal Systems
As I mentioned before, there are seven crystal systems. Following this table, you will see a few examples of the crystals listed here. But, first, here are the seven systems of the crystal structure.
|Cubic/Isometric: e.g. Diamond, Garnet||Cube, Octahedron||9 planes of symmetry, 13 axes, a center of symmetry|
|Hexagonal: e.g. Emerald, Aquamarine||Prism, Bipyramid||7 planes of symmetry, 7 axes, a center of symmetry|
|Tetragonal: e.g. Zircon, Rutile||Four-sided Prism, Tetragonal Bipyramid||5 planes of symmetry, 5 axes, a center of symmetry|
|Trigonal: e.g. Quartz, Sapphire||Prism, Rhombohedron||3 planes of symmetry, 4 axes, a center of symmetry|
|Triclinic: e.g. Turquoise, Sunstone||Pinacoid||No planes of symmetry or axes, a center of symmetry|
|Orthorhombic: e.g. Peridot, Topaz||Rhombic Prism, Pyramid, Dome Terminations||3 planes of symmetry, 3 axes, a center of symmetry|
|Monoclinic: e.g. Jadeite, Moonstone||Prism, Pinacoid||1 plane of symmetry, 1 axis, a center of symmetry|
Here are a few examples from the table above.
I hope you find inspiration and guidance from learning more about the world of crystals and how they fit into your lifestyle. If you have any questions or have a suggestion, please contact me right away.
Other Posts in the Crystal Healing Stones Series:
- The Amazing Healing World of Crystals • Introduction
- The World of Crystals Through the Ages
- Crystal Environments • Shamanism
- Science of Crystals • How Crystals Form
- Structure of Crystals • The Form Behind the Sparkle
- Light and Crystals • The Fascinating Science
- Crystal Light & Power • The Sparkle that Ignites
- Selecting the Right Crystal Healing Stones
- The Symbiotic World of Crystals