Pyrite gold cubes

Pyrite in golden cubic crystals: the popular 'fool's gold' reveals its geometric beauty and geological significance.

About this subject

Pyrite, also known as fool's gold, is an iron sulfide mineral (FeS2) that frequently forms perfect cubic crystals. These golden cubes, like those seen in the image, result from the cubic crystal habit common in pyrite. Its metallic yellow color and intense luster fooled many miners during the gold rushes of the 19th and 20th centuries, leading to false hopes and disappointments.

The formation of these cubes occurs in diverse geological environments such as hydrothermal veins, sedimentary rocks, and metamorphic rocks. Pyrite can also exhibit octahedral or pyritohedral forms, but cubes are the most iconic. Its hardness of 6-6.5 on the Mohs scale makes it relatively resistant but brittle.

Historically, pyrite was used as a source of sulfur for sulfuric acid production and, in ancient times, to start fires due to the sparks produced by striking it. Today, besides being collected for its aesthetics, it is studied for its role in mineral deposit formation and its presence in some lithium batteries.

Interestingly, pyrite does not contain gold in its composition but can be associated with gold deposits. Its name comes from the Greek 'pyrites lithos' (stone of fire). Collectors value well-formed cubic crystals, which can reach several centimeters in size.

Frequently Asked Questions

Is pyrite real gold?

No, pyrite is iron sulfide (FeS2) and does not contain gold. It only resembles gold, hence the nickname 'fool's gold'.

Where is cubic pyrite found?

Cubic pyrite crystals are found in many locations, including Spain, Peru, Mexico, and the United States (especially Colorado). In Brazil, it occurs in Minas Gerais and Bahia.

What is pyrite used for today?

Pyrite is mainly used for sulfuric acid production and as a sulfur ore. It is also used in low-cost jewelry and some types of batteries.