Purple Fluorite vs. Amethyst – The Similarities and Differences (With Photos)

By Keith Jackson - Geologist

| Updated

Purple Fluorite vs. Amethyst – The Similarities and Differences (With Photos)

By Keith Jackson - Geologist


Purple fluorite and amethyst stand out in the fascinating world of gemstones because of their beautiful and mysterious purple colors.

Even though they are the same color, these two minerals are very different. Each has its history, story of its formation, and set of properties.

Their differences show how varied the world of gemstones is, and they remind us that even in things that look alike, there is a lot of uniqueness to be found.

We’ll give you the information to tell these mineral beauties apart, even in their most subtle forms, by reviewing their detailed features.

This article will change how you see purple fluorite and amethyst, making you appreciate nature’s complex beauty even more!

Purple Fluorite vs. Amethyst – The Major Differences

To begin, let us talk about what makes them unique. These characteristics will stand out when you put these next to each other.

Appearance – Amethyst has six-sided prisms

A gorgeous raw amethyst crystal
Amethyst photo provided by and available for purchase at SacredMinerals333

Purple fluorite and amethyst look very different from one another. The crystal structures and clarity of each stone are the first things that set them apart.

Purple fluorite usually crystallizes in the shape of a cube or an octahedron, which makes clear geometric shapes.

In terms of how clear it’s, it can range from being completely clear to being see-through.

This can make a single piece of fluorite look like it has many sides and is hard to understand, especially if it has different clarity levels. Also, fluorite’s surfaces can look almost like glass; when light hits them, they often give off a bright sheen.

Different types of amethyst can be opaque or clear. The clearer types are often used in jewelry because they look like gems. Amethyst is also famous for its color zoning, which can look like stripes or patches of color inside a single crystal.

The colors can range from light pinkish-violet to deep purple. This feature is unique to amethyst and makes it easy to tell it apart from purple fluorite, which has a more uniform color.

Chemical Composition – Purple fluorite belongs to the halide minerals group

A stunning raw purple fluorite crystal
Purple fluorite photo provided by Weinrich Minerals

The chemical makeups of purple fluorite and amethyst are very different, showing that they are two other minerals. Purple fluorite is made of calcium fluoride and has the chemical formula CaF2, which puts it in the halide mineral group.

Because calcium and fluoride ions are bonded together in their structure, they form the crystals that make it unique. The simple elements that makeup fluorite differ greatly from those that makeup amethyst.

For example, fluorite has no silicon, an important part of amethyst’s structure.

The chemical formula for amethyst is SiO2, which means it is a type of quartz, which is also in the group SiO2. Its color is different from clear quartz because it has iron and other transition metals mixed in with it, along with natural radiation.

Because of these flaws or impurities in the crystal lattice, color centers are present, giving amethyst its distinctive purple color.

In quartz, the bond between silicon and oxygen is very strong. It forms a three-dimensional network of tetrahedra, with two silicon atoms sharing each oxygen atom.

This structure is very different from fluorite’s, and it helps explain many physical differences between the two minerals, such as their hardness and the way they form crystals.

Cleavage – Amethyst has no cleavage

A transparent amethyst crystal with a pointy end
Amethyst photo provided by Saphira Minerals

Purple fluorite and amethyst are very different in their cleavage, which is how they tend to break along smooth planes based on their crystal structure. People know purple fluorite for the way it perfectly breaks apart in four directions, making octahedrons.

Because of this, when fluorite crystals are broken, they usually break into smooth, well-defined pieces that show off the structure of the crystal.

This kind of cleavage is important because it shows that fluorite is a mineral that can be easily cut into geometric shapes. This is important to remember when working with gemstones, making jewelry, or using it for decoration.

Because the bonds between silicon and oxygen in quartz are so strong, quartz has no cleavage.

Amethyst doesn’t break along clear lines; instead, it has a conchoidal fracture that makes surfaces uneven and curved, like the inside of a shell. The fact that quartz doesn’t break apart is one of its main properties that sets it apart from many other minerals.

Amethyst doesn’t break into flat or uniform surfaces when force is applied. This is very different from fluorite, which breaks into cleavage faces.

Density – Purple fluorite has lower density

A stunning purple fluorite crystal cluster
Purple fluorite photo provided by ExoticCrystals

Density, or the amount of mass per unit volume of a substance, differs for purple fluorite and amethyst because they have different chemical makeups and internal structures. The density of purple fluorite is between 3.0 and 3.2 g/cm³.

On the other hand, a variety of quartz called amethyst has a lower density, measuring about 2.65 g/cm³.

Because amethyst contains silicon, which is less dense than calcium in fluorite, this difference in density may be partly due to the ingredients that make up the stone.

This differs from amethyst, which has a lower density of about 2.65 g/cm³. This difference in density may partly be caused by the things that make up the stone. For example, silicon in amethyst is less dense than calcium in fluorite.

It may not seem important, but the differences in density between purple fluorite and amethyst are important factors that affect not only how they are identified and categorized, but also how they are used, especially when the stone’s weight is important, like in jewelry-making.

Fluorescence – Amethyst can’t fluoresce

A lovely amethyst crystal cluster with deep purple hues
Amethyst photo provided by Fossilera

Purple fluorite and amethyst have very different fluorescence, which is the process of absorbing light at one wavelength and then re-emitting light at a different wavelength.

This is one of the things that makes them so different optically. Under ultraviolet (UV) light, purple fluorite is known for giving off an intense glow that is often blue or violet.

The color and strength of this fluorescence can change depending on where the fluorite comes from and if it has certain impurities or activators, like yttrium or europium, that can fill in for calcium in the crystal lattice.

Because these impurities are energy-sensitive, they react with UV light. This makes the crystal give off light at a different wavelength, making it glow.

It’s not common for amethyst to fluoresce when exposed to normal UV light. It could instead have a weak reddish or orange fluorescence, or it might not have any fluorescence.

This is because amethyst is mostly made up of silicon dioxide and some other chemicals that give it its purple color. This is why it doesn’t fluoresce strongly. Most of the time, these impurities are iron or other transition metals. They don’t react with UV light like the activators in fluorite do.

Hardness – Purple fluorite is softer

A sharp cubic purple fluorite with deep purple hues
Purple fluorite photo provided by CrystalAndMinerals

One big difference between purple fluorite and amethyst is how hard they are. Hardness means how easily they can be scratched. Purple fluorite is a 4 on the Mohs scale of minerals’ hardness.

In other words, it’s not too hard; a steel knife or a piece of quartz can scratch it. The chemical bonds and crystal structure of fluorite make it soft.

The calcium and fluoride ions are set up to make it easy for planes inside the crystal to move, making it less hard. Because of this, fluorite needs to be handled carefully because it is more likely to get scratched or broken.

Amethyst has a much higher hardness of 7 on the Mohs scale. The tetrahedral bonding of silicon and oxygen atoms forms a very strong three-dimensional network, giving amethyst its durability.

As a result, amethyst is more resistant to scratches. It’s less likely to be damaged by everyday handling, making it a popular choice for jewelry and decorative items requiring durability.

Amethyst vs. Purple Fluorite- The Similarities

Although they are different, they are similar in some ways. Knowing these gemstones have in common makes the world of gemstones more interesting.

Color – Both amethyst and purple fluorite are purple

A pretty amethyst crystal cluster on top of another white mineral
Amethyst photo provided by Wilensky Exquisite Minerals

Purple fluorite and amethyst share a captivating similarity: their iconic purple hue. Because they are the same color, it’s easy to connect with them and sometimes get them mixed up at first glance.

When these minerals are found in their purple forms, they can show various colors, from light lilac or lavender to stronger, deeper purples. Both can have very rich and deep colors that make them stand out.

This often makes people want to use them in jewelry and other decorative items. Also, color zoning can happen in both purple fluorite and amethyst. This is when different shades of purple show up in different parts of the same crystal.

This event makes the stones look more interesting by adding to their unique patterns.

The different shades of purple in different pieces of both minerals are usually caused by differences in the present chemicals and the conditions in which they formed.

Conductivity – Purple fluorite and amethyst are poor electricity conductors

A stunning cubic purple fluorite crystal specimen on a matrix
Purple fluorite photo provided by Fine Mineral Photography – Mineralandy Collection @finemineralphotography

Regarding how electricity flows through them, purple fluorite and amethyst are similar. This is mostly because they are both insulators.

Because they are made up of crystals and certain chemicals, these two minerals don’t conduct electricity well. Purple fluorite is made up of calcium fluoride and since it has no free electrons or other charge carriers, electricity can’t flow through it easily.

In the same way, amethyst, which is a type of quartz (silicon dioxide, SiO2), doesn’t have a metallic element that conducts electricity.

Instead, the strong covalent bonds between silicon and oxygen atoms make it impossible for electrons to move, which stops electricity from flowing through them.

Both minerals don’t change how much electricity they conduct when the temperature changes, which is a normal thing for non-metallic minerals and insulators to do.

This is because their electronic structures don’t let electrons flow freely, and electrons are what carry electricity in conductive materials.

But when they are pure and natural, purple fluorite and amethyst both have low conductivity. This is a property that many other non-metallic minerals also have.

Formation – Amethyst and purple fluorite both form in hydrothermal veins

A mesmerizing natural raw amethyst crystal
Amethyst photo provided by Wildling Heart

Even though purple fluorite and amethyst are different minerals, they were formed similarly. For example, they were both formed by hydrothermal activity and are often found in the same environments.

Hydrothermal veins are cracks in rocks that are filled with superheated water and minerals that have been dissolved.

These minerals can form in these veins. When these solutions cool down or the pressure changes, minerals settle to the bottom, and crystals like amethyst and purple fluorite can form.

Because of the way the geochemistry of the hydrothermal fluids works, these minerals are often found with metallic ores. They can also form in vugs, holes in rocks, or cracks where mineral-rich hydrothermal fluids have been moving through.

Due to the surrounding rock matrix doesn’t affect the growth of crystals in these cavities, they can get very big. This is why well-formed purple fluorite and amethyst crystals are often found in these places.

Both purple fluorite and amethyst are secondary minerals. They can form when minerals in host rocks are replaced or when rocks are worn down by weathering.

Location – Both purple fluorite and amethyst can be found worldwide

A brilliant cubic purple fluorite crystals specimen
Purple fluorite photo provided by Collector’s Edge Minerals – @collectorsedgeminerals

Even though purple fluorite and amethyst are chemically and physically different, they can be found in many of the same places worldwide, often in areas with a lot of geological activity.

These rocks have histories that can be learned from where you find them. These are the best places to go rockhounding because you can find purple fluorite and amethyst.

Both of these minerals are found worldwide, on many continents. This shows that they are present in a wide range of geological settings.

Both minerals are often found in places that have been volcanically active or have a lot of hydrothermal veins. For example, amethyst deposits are well-known in Brazil, especially in Minas Gerais and Rio Grande do Sul.

They can also be found in Uruguay, Madagascar, Zambia, and the United States.

Also, large amounts of purple fluorite can be found in China, Mexico, Mongolia, Russia, South Africa, Spain, and the United States, especially in Illinois, which used to be called the “Fluorspar Capital of the World.”

Their presence in these areas is because of the geological conditions there, like magma cooling or hot, mineral-rich fluids moving through cracks in the Earth’s crust. These conditions help create many mineral deposits.

Luster – Amethyst and purple fluorite possess a vitreous luster

A vibrant specimen of amethyst crystal
Amethyst photo provided by StudioMineralia

The luster of purple fluorite and amethyst is similar. Luster is a property that describes how light interacts with the surface of a mineral. It’s common for both minerals to have a vitreous luster, making them look like glass.

This kind of luster has a surface that is reflective and almost shiny. This is especially clear when the minerals are polished or cut or broken.

Both purple fluorite and amethyst have a vitreous luster that comes from how their crystal structures interact with light.

Because of how the atoms are arranged and chemically linked, light can pass through minerals and bounce back, giving them a consistent, smooth shine common to many crystalline substances.

This glass-like quality makes them more appealing, especially when used to make jewelry and home decor.

Both amethyst and purple fluorite have this vitreous luster when crystallized, though the surface might not look as shiny because it is naturally rough or has impurities.

But when both minerals are cut and polished, especially made into gems or other decorative items, they show off their full shine.

One thing that purple fluorite and amethyst have in common is that they are both very valuable for their beauty. Collectors and businesses use them for many different things.

Magnetism – Neither purple fluorite nor amethyst is magnetic

A stunning pastel purple fluorite with a unique shape
Purple fluorite photo provided by Spirifer Minerals – @spirifer_minerals

Regarding magnetism, purple fluorite, and amethyst are pretty much the same: they are not magnetic.

This is because of the way their crystals and chemicals are structured. Minerals are often magnetic because of elements like iron, nickel, or cobalt that are present and how they are arranged and oxidized in the mineral’s structure.

Amethyst is a form of silicon dioxide with trace impurities that give it its color. Purple fluorite is a calcium fluoride. Their chemical makeups and lattice structures don’t allow the formation of magnetic domains, which makes a material magnetic.

It’s also important to remember that more than its magnetic elements affect a mineral’s magnetic properties. They are also affected by their valence and how their atoms are arranged in the crystal lattice.

Both amethyst and purple fluorite don’t have magnetic properties because the elements and their arrangement don’t help the magnetic spins line up.

There is a theoretical chance that some impurities or inclusions in these minerals could have a magnetic charge. Still, the mineral has no magnetic charge, whether it’s amethyst or purple fluorite.

Many types of crystalline minerals don’t contain ferromagnetic materials. They all lack magnetism, a key feature used in geology to identify and classify these minerals.

Price – Both amethyst and purple fluorite is affordable

A beautiful cluster of amethyst crystals
Amethyst photo provided by Superb Minerals – @superbminerals

The prices of purple fluorite and amethyst are similar. This is mostly because of quality, clarity, and color intensity. Both of these minerals can be found for a reasonable price, but high-quality specimens cost a lot more.

The color richness, clarity, carat weight (for gemstones), and how well they are cut (for gemstones) determine how much purple fluorite and amethyst are worth.

Regarding both minerals, pieces with deep, bright colors and good clarity sell for more. Deep purple amethyst from certain places is considered more valuable, and intense purple fluorite with clear, well-defined cubic crystals can also be very valuable.

A specimen’s price can also increase if it’s rare, big, or has special qualities that make it stand out, like phantom inclusions in amethyst or color zoning in fluorite.

Both can be found reasonably for lower-quality materials, but gem-quality stones and rare minerals can be much more expensive.

The place where purple fluorite and amethyst come from also affects their value. Some places are known for producing especially beautiful stones, and stones from these places may sell for more because people think they are better quality or more rare.

In the bigger market, like jewelry and home decor, the prices of amethyst and purple fluorite are affected by how much people want them, how spiritual they are thought to be, and what’s in style.

Streak – Purple fluorite and amethyst has white streak

A gorgeous purple fluorite covered in snow-like minerals
Purple fluorite photo provided by LunaSkyCrystals

In this way, purple fluorite and amethyst are alike: they both have a white streak.

It may surprise many that the streak these minerals leave behind is not purple, even though the minerals are rich purple.

This is because the streak test shows the mineral’s color when it’s powdered, and both amethyst and purple fluorite have parts that lose their purple color when ground up into a fine powder.

When the mineral is finely powdered, the white streak shows its true color. This is always the case, even when looking at larger, solid specimens that show color variations.

The streak test is an important way to figure out what kind of mineral it’s because the color of the streak is more stable than the mineral’s color when it’s solid, which can change a lot because of impurities or radiation exposure.

Even though purple fluorite and amethyst have beautiful, bright purple colors in jewelry or specimens, they have something in common that can’t be seen with the naked eye. The white streaks show this that they both make.

The Easiest Ways To Tell Purple Fluorite and Amethyst Apart

Purple Fluorite at the top and Amethyst at the bottom

You can tell purple fluorite and amethyst in a few different ways. It’s fun to try to figure out what makes them unique. You should know they are not the same in some important ways, even though they look the same.

Look at the shape of their crystals

Crystals of different shapes are made when minerals form. The way amethyst crystals form is called “hexagonal,” meaning that each crystal has six sides. Like the shape of a pencil, the ends of amethyst crystals have hexagonal points.

Purple fluorite, on the other hand, forms in a different way. Its crystals can be “isometric,” meaning they have eight sides and look like two pyramids stuck together at the base.

See if it glows under UV light

Another cool thing about these minerals is that they glow in ultraviolet light. This is called fluorescence. Purple fluorite is wonderful because it can glow in UV light, changing color to blue, purple, or white.

On the other hand, Amethyst doesn’t glow in UV light very often. So, if you have a UV flashlight, also called a black light, you can have fun reading things that glow.

Perform a hardness test

The Mohs scale is used to measure how hard minerals are. Let’s do a scratch test to see which minerals can damage other minerals. That’s right, amethyst, a type of quartz, is pretty tough!

Amethyst would leave a mark on glass or steel if you tried to scratch them with it. Purple fluorite, on the other hand, is only 4 hard. That means it’s not hard and won’t scratch steel or glass. You can check if you have a mineral kit or a hardness test set.

About Keith Jackson - Geologist

Keith Jackson is an avid rockhound who is constantly exploring new sites to expand his collection. He is an active Geologist with a wealth of experience and information from across the country that he loves to share with the Rock Chasing crew.

Leave a Comment