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The Origin and Science Behind How Amethyst Forms

INSIDE: Discover how Amethyst forms so you can better understand just how incredible these little (and often big) gems are. You'll be in awe of how amazing Mother Nature is and why owning an Amethyst Geode is so special.


Amethyst is one of the most popular healing gemstones in the spiritual community (and it's certainly our favorite).

We can easily say that Amethyst volcanic geodes represent some of the most beautiful and most complex gifts of nature.

The very process of formation is a long and complex one. A study posted on Science Direct implies that even gas reservoirs in simple volcanic rocks are a result of more complex chemical processes than we thought.

Amethyst geode formation is pretty magical, and if it has sparked your attention, read on to discover how Amethyst forms...

About Amethyst Geodes

Amethyst geodes belong to the family of Quartz crystals and they are typically found in North, South, and Central America, with Brazil being one of the most famous homes of Amethyst mines.

What makes it unique is its distinctive purple color. It is a formation of a hexagonal crystal system that can be found in large cavities and smaller rock look-alikes called geodes.

Because they are thousands of years old, sometimes even prehistoric, Amethyst geode formation carries energetic information that spans all of those years.

Amethyst Geodes

What is Amethyst Made of?

Amethyst is a result of three key factors working together.

Hollow Rock

The first key "ingredient" is a hollow rock. Just like other geodes, Amethyst requires a hollow space in which a crystal cavity can form.

It is formed inside igneous volcanic rocks called basalts, which are created by volcanic lava. These rocks act as vessels that contain minerals and water over time, creating the well-known white-purple crystal formation.

The inside walls of the basalt become the base for how Amethyst forms. Aside from basalts, this gemstone can also, though not very commonly, be formed in hydrothermal veins and sedimentary rocks.

Silica & Ferric Iron

The second factor in how Amethyst forms is the environment it is formed in. For an Amethyst to form, there needs to be a presence of silica and ferric iron in the water.

Silicon dioxide is one of the key ingredients in its chemical structure, which is crucial for the rock-forming process.

Besides these essential compounds and groundwater, there needs to be gamma irradiation in order to stimulate important processes inside the volcanic rock. The process includes different levels of calcium, oxygen, and carbon. 


Lastly, the third one is time. Crystal formation is a unique chemical process that takes time... a lot of it.

For a natural Amethyst to form, it can take millions of years, which is what makes them so precious.

Although there are plenty of crystal imitations, only geodes that were created by Mother Nature are considered to be healing. All of the natural Amethyst geodes are older than humanity as we know it!

How Do Amethyst Crystals Form?

Now that we know what elements are needed, let's look at how Amethyst forms in terms of the scientific process.

The very formation of Amethyst is a two-step process...

  1. First, a hollow rock or magmatic geode is formed due to the cooling of lava in interaction with air, gases, and temperature change.
  2. Then comes the second stage, and that is the actual creation of the crystal cavity. Amethyst is formed at temperatures that are lower than 100°C, and possibly even lower than 60°C.

Mineral-Rich Water & Porous Rocks

This creation starts when porous igneous rocks come in contact with groundwater.

The water around volcanoes is rich in silicates. As water penetrates the hollow rocks, dissolved silica and other minerals flow through them.

The mineralized water that flows through tunnels contains approximately 3% of sodium chloride. This is possible because volcanic rocks have special lava tunnels and gas-bubbles that occur naturally in types of rocks and are the result of basalt formation.

These serve as tubes through which minerals come in contact with the inside of the hollow rocks, forming cavities. The first layer that forms on volcanic rock’s inner walls is Agate.

Minerals get deposited and after a foundation is laid, Agate allows Quartz creation to take place.

Gamma Irradiation

The final step that turns Quartz crystal into Amethyst lies in the gamma irradiation, a natural occurrence in nature thathas very high photon energy.

This radiation activates the chemical process in which ferric iron or Fe(+3) slowly replaces Silica and allows for the crystallization process to unfold.

When we look at how Amethyst forms, we can see that crystals found on the inner wall of the geode are usually dispersed all over it, leaving only the central part of the volcanic rock hollow.

This hollow is usually dry, but it is possible to see groundwater residue as the geode is cracked open, since water was an important part of its creation.

Finally, as time works its magic and years pass by, due to changes in the chemical compounds and temperature, the fluid slowly evaporates thickening and strengthening the crystals.

When we ask, how do Amethyst geodes form, it is largely dependent on the time and number of these cycles.

As this process repeats, the Amethyst inside a basalt becomes thicker but inconsistent in color intensity and may take different shapes, due to temperature and chemical changes.

The result is an Amethyst crystal of different color density and termination (point) sizes, as well as slight differences in its powerful healing properties.

Today, miners find different variations of Amethy, from Druzy, Scepters, and those with split growth to Prismatic and perfectly-developed crystals. There can be cap-shaped ones, as well as those whose crystals are elongated.

Although most are round or elliptical, it is not uncommon to find Amethyst Cathedral geodes, which are uniquely elongated geodes that resemble a church arch.

Amethyst Geodes

Amethyst Identification

Although for an untrained eye simple rocks and geodes may be hard to identify, there are a few key factors to include in its discrimination.


Amethyst geodes, like all others, vary in size. They are all roundish, rough-surfaced, and lighter than regular rocks.

Shaking Sound

When shaken, some may make light sounds in cases where there are loose pieces of crystals or residue water rumbling in the remaining void of the geode. 

This is because there is a hollow space that remains inside the geode even after the crystal formation process is done. 

What the chemical and physical processes do during formation is fill the hollow with mineral and essential compounds that shrink the void to a certain degree, but don’t completely fill it.

Odd-Looking Rock

Some people say Amethyst Geodes look like hardened salty surfaces, or even like unappealing rocks. On the outside, they have a different texture than an average rock, and when compared side-by-side, it can be described as odd-looking.

Termination Size & Appearance

Although there have been historical findings of Amethyst geodes that were more than 3 meters high, and while the geode itself may vary in size, the individual crystal points inside the geode are rarely larger than 11 inches.

High-quality ones are clear, translucent, and may or may not have visible inclusions, depending on their place of origin and how amethyst forms within the geode.

Purple Color

The key visual distinction between Amethyst and other types of gemstones lies in a recognizable purple color. The lightness or depth of the purple color depends on the irradiation, as well as the amount of and the purity of iron involved in the crystal cavity formation.

The color is never even, and it varies from whiter and light purple at the roots of the crystal, and gets darker purple at the tips.

Final Thoughts

When you understand how Amethyst forms, this stone takes on a whole new meaning. It's a miraculous process that can leave us in a state of awe. Owning an Amethyst Geode can bring some of that awe-inspiring wonder into our lives. 

Browse our current inventory of one-of-a-kind Amethyst Geodes here.

Amethyst Geodes

* Crystals and stones should not be used as a substitute for medical advice or treatment. Please read our full disclosure notice here.
How Amethyst Forms
Science of How Amethyst Forms
Discover How Amethyst Forms

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