Pyrite Suns For Sale

Pyrite suns or pyrite dollars are a unusual pyrite formation exhibiting striations radiating out from the center like rays of the sun. They are found in narrow, compacted seams of slate interbedded in the 300-million-year-old coal deposits near Sparta, Illinois. People used to believe that pyrite suns were fossils that had undergone pyrite replacement. The current consensus is that they are simply formed due to the enormous pressure compacting the slate, causing pyrite to grow laterally in a radiating manner.

Lot: Pyrite Suns From Illinois - Pieces #91206

Lot: 3" Pyrite Suns From Illinois - 10 Pieces

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Large 5.4" Pyrite Sun - Illinois

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4" Pyrite Sun - Sparta, Illinois

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Large, Pyrite Sun - Sparta, Illinois #134892

Large, 4.3" Pyrite Sun - Sparta, Illinois

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Beautiful, Pyrite Sun - Sparta, Illinois #91012

Beautiful, 4.3" Pyrite Sun - Sparta, Illinois

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Huge, Pyrite Sun - Sparta, Illinois #91020

Huge, 4.5" Pyrite Sun - Sparta, Illinois

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Beautiful, 3.4" Pyrite Sun - Illinois

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Pyrite Sun In Riker Mount Case - Illinois #31174

3.6" Pyrite Sun In Riker Mount Case - Illinois

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What Are Pyrite Suns?

Pyrite suns (also called Sun Dollars, Miner’s Dollars or incorrectly Marcasite Suns) are brilliant, disk-shaped concretions of radiating pyrite crystals found in the coal mines near Sparta, Illinois.

Are Pyrite Suns Fossils?

A long time ago, it was believed that pyrite suns were fossil sand dollars or lily pads, but we now know they are just an interesting mineral formation!

Where Are Pyrite Suns Found?

Very small, disk-shaped pyrite formations can be found in marine shales worldwide, but the larger formations known as pyrite suns have only been reported from the coal mines near Sparta, Illinois and in China.

In Illinois, they are found 200-300 feet underground in coal mines. The pyrite suns are found in a layer of black, pyrite-rich shale called the Anna Shale, just a few inches above the main coal seam. These pyrite suns are either collected by the miners themselves or from the spoil piles of these mines. Since nearly all of the coal mines near Sparta have shut down, the supply of these pyrite suns coming onto the market has dwindled significantly.

How Are Pyrite Suns Formed?

Pyrite suns' disk-shaped patterns occur because the weight of overlying sediment made it easier for crystals to grow laterally as opposed to vertically. This results in flattened pyrite concretions between the layers of shale instead of more typical spherical shapes.

How Big Are Pyrite Suns?

The pyrite suns from Sparta average around 3 inches in diameter. At over 4 inches they start to become increasingly rare, and the largest we've seen was about the size of a dinner plate!

Are These The Same As Marcasite Suns?

For many years, pyrite suns were incorrectly referred to as marcasite suns. They have a crystal habit that more closely resembles marcasite, but x-ray studies have shown they are mostly pyrite with only a very minor amount (<5%) of marcasite. It’s possible that they may be a pyrite pseudomorph after marcasite, which means they were originally marcasite but chemically transformed to pyrite.

Will Pyrite Suns Disintegrate Or Suffer From Pyrite Disease?

It has been reported that some pyrite suns are unstable and will disintegrate due to what is known as “pyrite disease”. Over time pyrite will begin to oxidize in the atmosphere, first turning into ferrous sulphate, then ferric sulphate, and finally sulphuric acid. The acid accelerates the reaction. So yes, pyrite suns will unfortunately deteriorate over time when exposed to oxygen.

How many years it takes varies widely. We've seen pyrite suns in old collections that were 50-100 years old with no deterioration at all, while others had crumbled in 5 years. The amount of moisture in the air is a primary factor: if the pyrite sun is kept in a dry environment it will last a lot longer, indefinitely in a moistureless one. Secondly, the more marcasite present in the pyrite sun, the faster it seems to decompose.

Storing them in one of our floating frame display cases would be a good option to limit their exposure to oxygen and moisture.

What About Iridescent Pyrite Suns? Are They Natural?

Natural iridescent in pyrite suns are very rare and are caused by higher concentrations of marcasite in a specimen. In recent years, people have begun to alter the appearances of pyrite suns with bleach to artificially give them unnatural iridescence. If a pyrite sun has a very pronounced iridescence, chances are it was artificially induced. While these iridescent suns looks cool, they highly unstable and will break down in the atmosphere much quicker than natural ones.

What Are Pyrite Suns?

Are Pyrite Suns Fossils?

Where Are Pyrite Suns Found?

How Are Pyrite Suns Formed?

How Big Are Pyrite Suns?

Are These The Same As Marcasite Suns?

Will Pyrite Suns Disintegrate Or Suffer From Pyrite Disease?

What About Iridescent Pyrite Suns? Are They Natural?