Pyrite: The Mineral Known as the Gold Imposter

”Pyrite in its natural form"
Photo by PiLens – yayimages.com

Human fascination with gold is as ancient as the civilization itself. Throughout the timeline of history, this bright and yellow mineral has always been considered a precious and prized commodity. Such was the appeal and requisition for the mineral that people even tried to produce synthetically. It is often said that the foundation of modern chemistry was laid down with the attempts of producing gold in labs.

Due to its prized stature, gold is also often used to carry out fraud, directly or indirectly. For instance, its imitations are often sold as original to rip off uninformed consumers as many naturally occurring minerals resemble gold.

Pyrite is one such example that bears a resemblance to gold in its naturally occurring and refined states. For that reason, it is also called fool’s gold since people who can’t tell gold and pyrite apart can easily be scammed by the latter as the expensive precious metal. In this article, we are going to discuss pyrite and the methods that can be used to tell it apart from gold.

Pyrite: A Sulfide Mineral

Pyrite is one of the most common sulfide minerals in nature.  If one breaks down pyrite chemically, then a single molecule of pyrite is composed of one atom of iron and two sulfide ions. The natural form of pyrite displays a dull brass yellow color. However, it can be processed and furnished to give a bright metallic luster. This is the reason why it starts to look like a gold specimen, particularly to all those who are not expert in distinguishing different minerals.

Whether, it’s ingenious, sedimentary or metamorphic rock formations, small deposits of pyrite can be found in every geographic setting. This is the reason why pyrite is an inexpensive mineral and worth nothing when compared to gold.  It is important to mention that some traces of original gold can be found in some naturally occurring pyrite deposits though, but never enough to consider this element to be worth anything of value.  

Practical Uses of Pyrite

There are two notable practical uses of pyrite. Let’s take a look.

Pyrite as Sparking Material

Pyrite has been used as a sparking material for centuries. Sparking characteristic of the mineral is also the reason behind the name ‘pyrite’. The word is derived from a Greek word ‘pyre’, which means ‘fire’. With industrial processes getting modernized really fast, this use of pyrite has also been reduced. Nevertheless, it is still used in flintlock guns as a sparking material.

Production of Sulfur and Sulfuric Acid

These days, pyrite deposits are largely used to produce sulfur and sulfuric acid on a commercial level.

Use of Pyrite in Feng Shui Practice

Feng Shui is a thousands-year-old Chinese tradition of controlling the energies in the environment for a happier and content life. This ancient practice associates the energies emitting out of pyrite with wealth and abundance. The Feng Shui use of pyrite entails keeping it in the home as a decoration or wearing it in the form of a pedant.  

Differentiating Gold and Fool’s Gold  

Mineralogists often carry out destructive and non-destructive tests to distinguish apparently similar minerals. Several destructive and non-destructive tests are used to differentiate gold and pyrite. Destructive tests usually involve physical and chemical tests. Therefore, they are not used if there are strong chances that the given specimen is actual gold and not pyrite. Let’s have a look at all such tests used to tell the difference between actual gold and fool’s gold (pyrite).

Non-destructive tests

Color

The color of the naturally occurring specimen is another characteristic that can be used to tell gold and fool’s gold apart. Natural and unrefined gold specimen has bright yellow to golden tinge. In contrast, pyrite exhibits brassy tinge. Many naturally occurring gold specimens are often alloyed with silver deposits, giving the extracted piece a whitish yellow color.

Tarnish

Some minerals already have tarnish on their surface when they are found in nature. So, analyzing this feature can be used as one of the non-destructive tests. Naturally occurring gold flecks and lumps are usually untarnished and already bright. On the other hand, pyrite specimens often contain some sort of tarnish on their surface.

Shape

Gold and pyrite specimens can be differentiated on the basis of shape as well. However, this non-destructive test alone should not be used to differentiate the two because some of their naturally occurring crystalline specimens can exhibit a similar crystal habit. Otherwise, pyrite is usually found with angular edges, giving its specimen the shape of cube, pyritohedron or octahedron. In contrast, gold specimens are found in rounded shapes.

Striations

Many pyrites deposits are found with fine parallel striations on their surface. Striations are not present on gold.

Specific Gravity Test

The specific gravity (SC) of the pure gold specimen is 19.3 while pyrite has SC value of 5. Even the naturally occurring alloyed form of gold has specific gravity more than 5. So, this is another way to differentiate between gold and pyrite. Specific gravity is a simple lab test that can be carried out with a beaker and weighing machine.  

Destructive Tests

Hardness

The hardness of both minerals is also considerably different from each other. Gold and fool’s gold have a hardness of 2.5 and 6.0 on the Mohs scale respectively. Copper has a Mohs hardness of 3.0. This means gold specimen can’t scratch copper. However, fool’s gold or pyrite can do that.

Streak Test

Streak test of minerals entails observing their color in finely powdered form. Gold streaks appear yellow, whereas fool’s gold exhibits greenish black tinge in its amorphous form.

Ductility

Gold is extremely ductile. It can easily be bent into shapes even with a pin or soft wooden stick. On the other hand, pyrite either resists or gets broken into pieces upon the application of pressure.

Sectility

Sectility is a physical property of any material to be cut into pieces. Gold has an extremely good value of sectility as compared to fool’s gold. This implies that even the small pieces of gold can be cut into additional pieces. However, small pyrite pieces can’t be further minimized.

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