Dignayan Biyernes- Pyrite

Posted on: January 28, 2022 | National Museum of the Philippines

Have you ever seen a rock with shiny, gold-colored minerals on it? Can it be gold? Or is it something else? In today’s #DignayanBiyernes, let us talk about Pyrite.

Pyrite, with the chemical formula FeS2, is the most abundant sulfide mineral. Its name originates from the Greek word pyr, which means “fire”, because of the sparks it generates when struck. It has a brass-yellow color and a metallic luster. Crystals of pyrite are frequently cubic, pyritohedron, or octahedron with often striated crystal faces, although they can also form as massive, granular, or nodules. Pyrite can occur as an accessory mineral in many kinds of igneous, sedimentary, and metamorphic rocks, forming in a wide variety of environments.

Did you know that pyrite is commonly referred to as “fool’s gold”? Inexperienced people often mistake it for gold due to its color, metallic luster, and specific gravity.

So, how do you differentiate pyrite from gold? Well, you can easily distinguish one from the other using their physical properties, namely their hardness, streak, and density.

Pyrite is brittle with a hardness of 6-6.5, while gold is soft, malleable, and ductile with a hardness of 2.5-3. Scratching pyrite on a hard surface leaves a greenish-black to brownish-black streak, while gold leaves a gold-yellow streak. Lastly, pyrite is two to three times lighter than gold.

In the Philippines, pyrite is widely distributed. It is most commonly found occurring where copper and gold deposits are found. These include the provinces of Ilocos Region, Benguet, Bicol, Cebu, Samar, Negros Region, Surigao Del Norte, and Zamboanga Peninsula, among others.

If you want to see a pyrite mineral in person, you may book a tour at the National Museum of Natural History through this website.. Try and see if you can tell the difference between pyrite and gold.

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Text and image by the NMP Geology and Paleontology Division