How Is Amethyst Formed: Crystal Structure and Chemical Composition

Amethyst is a type of quartz whose chemical composition is silicon dioxide. Quartz is formed in lava, especially when gas bubbles are trapped, forming crystals inside the cavities created by the bubbles. As the cavities fill with silica-rich fluid, crystals form in volcanic rocks. Check this article to know the detailing how is Amethyst formed.

Suggested Reading: Amethyst Crystal Meaning: Healing Properties, Benefits and Uses

How Is Amethyst Formed?



These purple stones are unique as they usually grow over vast areas, appearing plain from the outside but containing crystal gems inside. Amethyst geode structure is the characteristic that separates a stone from other gems, such as white diamonds that do not form geodes. The gems in these geodes follow a six-sided pyramidal crystal structure.

Read this to learn how to tell if Amethyst is Real or Fake

Criteria To Decide Quality of Amethyst


The essential factor in determining the value of an Amethyst is its color. The gemstone should be red to dark purple and should not have any color zoning. Color zoning occurs when bronze colors are inside the stone, significantly reducing the gem’s value. 

Stones should not be too dark, as they are dull and dark in the light. Amethyst is a stunning violet/purple quartz type. Amethyst crystals grow primarily on the inner surface of an amethyst geode in nature. 


High-quality versions of this stone are “eye-clean,” which means it is free of visible inclusions. Further, gemstones containing inserts are generally low quality and are often cabochons or beads. Since Brazilian Amethyst usually has low inclusions, the number of inclusions in the stone can sometimes be a product of its origin.


There are many ways to cultivate Amethyst. The cuts have oval shapes, triangles, cushions, emerald cuts, and other unique freeform shapes.


When buying Amethyst, it is essential to note that the price will not increase significantly with large carat sizes. It makes Amethyst an excellent choice for large jewelry designs.

Chemistry Of Amethyst

This purple form of quartz has the chemical formula SiO2. Amethyst obtained its color from manganese in the 20th century. However, because of its high sensitivity to heat and radiation, some authorities believed the color came from biological sources. Ferric thiocyanate and sulfur were extracted from the ore.

formation of amethyst

Recent studies have shown that ferric iron contamination causes amethyst color. Further studies have shown a more complex interaction of metal and aluminum than the color bond. 

Amethyst is usually yellow when exposed to heat, and most citrine, cairngorm, or yellow quartz jewelry is called “hot amethyst.” The arteries of amethystine quartz are prone to losing their color in the external environment.

The preparation of synthetic Amethyst is to mimic the best quality Amethyst. Chemically and physically, it is so similar to natural Amethyst that one cannot tell the difference without advanced gemological testing. 

There is a single test based on “Brazilian law twinning.” It shows 100% accuracy. Synthetic Amethyst can be identified quickly by combining right and left-hand quartz crystal structures with a single crystal. This type is not widely available to create this information practically. 

Read here to know the process to clean your Amethyst crystal.

What causes Amethyst to be purple?

Amethyst is formed by the unusual superposition of the different lamellae of the right and left hand. There is a possibility that mechanical stress is responsible for the structure. 

As a result of this composite formation, Amethyst can break down with curved fractures or show six thumbs. The contrast of two curved ripples may produce a broken pattern similar to engine rotation.

The Mohs hardness of 7 makes Amethyst a popular gemstone for jewelry.

Amethyst occurs in a series of primary colors ranging from light pink to deep purple grapes. Amethyst can show one or both secondary colors, red and blue. 

The suitable range is called “Deep Siberian” and has 75 – 80 percent purple, 15-20 percent blue, and (depending on the source of light) second red colors. 

Amethyst is commonly present near other quartz family stones. Citrine, precious yellow quartz, is commonly found in amethysts. Amethyst also occurs on clear and cloudy gray quartz. 

Exposure to rays from the sun or surrounding organisms causes chemical reactions that turn amethysts into purple. Neighboring quartz that is not exposed to irradiation or does not contain the manganese and iron needed to cause the color purple will not be Amethyst.

Where does Amethyst come from?

Amethyst may also be present on vugs, holes in the rock formed by dissolving or eroding on the rock’s surface and forming deep cavities. The primary utilization of Amethyst is present as a gemstone because of its brilliance in color and sheer transparency. 

Amethyst is found chiefly in Brazil as geodes within volcanic rocks, including Uruguay, South Korea, Russia, the United States, and South India. Zambia is one of the world’s major amethyst producers, with an annual output of 1000 tonnes.

The most valuable Amethyst, known as Siberian Amethyst, is a deep purple glossy blue, and red. Moreover, amethyst crystals usually occur near other kinds of rocks.

Amethyst Geodes

Amethysts form long, prismatic crystals. The most critical place for collectors to find Amethyst is geodes or bare rocks filled with crystals. Geodes are present in volcanic rock holes. 

As the rock cools and solidifies, it is filled with tropical substances — gasses, minerals, and volcanic material — resulting in a void. As it cools and substances come out of the rock, the minerals in the water sparkle. The proper minerals and water temperatures form Amethyst.

Volcanic Rock

Some experts believe Amethyst occurs in volcanic rocks. These deposits are available worldwide, but the largest deposits are in Brazil and Uruguay. Before South America became a significant player, most commercial Amethysts came from Russia and Siberia.


Although most amethyst deposits are present on bare rocks, many amethyst deposits occur in metamorphic rocks. It is rare in sedimentary rocks since they lack the chemical conditions required for Amethyst to form. There are different forms and appearances of Amethyst available in different parts of the world.

What is Amethyst made of?

Amethyst is the result of three essential factors that work together.

Hollow Rock

The first key to the “ingredient” is bare rock. Like other geodes, Amethyst requires a space where a crystal cavity can form.

It formed inside the volcanic rocks called basalts, formed by volcanic mud. Over time, these rocks contain minerals and water, which lead to the formation of white-purple crystals.

The inner walls of basalt form the basis of how Amethyst builds. In addition to basalts, this gemstone can also, albeit very rarely, form in hydrothermal vents and sedimentary rocks.

Silica & Ferric Iron

The second aspect is how Amethyst shapes the environment in which it operates. For Amethyst to form, there must be the presence of silica and ferric iron in the water. Its chemical composition contains silicon dioxide, essential for a rock formation.

In addition to these crucial compounds and groundwater, gamma rays need to be activated to stimulate vital processes within the volcanic rock. This process includes different levels of calcium, oxygen, and carbon.


Lastly, the third is time. It takes a lot of time to form crystals due to their unique chemical composition. For natural Amethyst to form, it can take millions of years, making it valuable.

Although there are many crystal simulations, only geodes created by Mother Nature are considered healing. All the natural geodes of Amethyst are older than humanity as we know it.

How long does it take for Amethyst to form?

The gems contained within these geodes have a six-sided pyramidal crystal structure. Some amethyst geodes, particularly those found in Brazil, are enormous enough to allow a person to stand within. 

Geodes naturally created take millions of years to form, and most geodes have been forming since prehistoric times.

How is Amethyst mined?

The extraction of a majority of Amethysts is in drift mines. Gemstones are usually hand-dug from mountains after excavation of a mine shaft to the gemstone-bearing rock.

The transportation of a mined Amethyst ore to a washing plant adjacent to the mine occurs. Using a diesel-powered conveyor system, the washing facility washes and sorts the ore before knocking and grading it.

The Amethyst is sorted and graded by a competent and well-trained crew. Supervising workers who create high-quality products is the responsibility of senior supervisors.

How to Identify a Good Amethyst?

While simple stones and geodes may be challenging to detect with the untrained eye, some essential factors to consider when distinguishing them.

Check the Weight

Amethyst geodes vary in size. They are all-round, have rough terrain, and are lighter than ordinary stones.

Look for Animation

When shaken, some may make simple noises in situations where there are fragments of crystals or residual water residue in the remaining area of ​​the geode.

A blank space stays inside the geode even after the crystal formation completes the process.

During formation, the actions of chemical and physical processes fill the hole with essential minerals and compounds that reduce space to some extent but do not fill it.

Check for an Odd-Looking Rock

Some people say that Amethyst Geodes look like solid salt or unattractive stones. Externally, they have a different texture than the central rock and compared to the sides, and you can describe it as an unusual appearance.

Observe the Trim Size and Appearance

Although there have been historical findings of Amethyst geodes that were more than 3 feet high, and the geode itself may vary in size, individual crystalline points within the geode are rarely more significant than 11 inches.

The high ones are clear, flexible, and may or may not be material, depending on where they come from and how amethyst forms within the geode.


When you understand the formation of a stone, you can connect with the crystal more efficiently. It is a beautiful process that can take us by surprise. Having Amethyst Geode can bring some of that fantastic miracle into our lives.