Pyrite and marcasite are two minerals that often confuse people due to their similar appearance. Both are iron sulphides, but they differ in crystal structure and physical properties. This blog will look at the differences between pyrite and marcasite, their historical significance, their forms, their suitability for use in jewellery, and their metaphysical properties.
The table below sets out the main differences between the two minerals.
| Chemical Composition | Crystal Structure | Forms | Physical Properties | Appearance |
Pyrite | FeS₂ | isometric | cubes, octahedrons, pyritohedrons massive nodules, granular concretions | More stable, harder (6-6.5 on the Mohs scale), and denser. | brass-yellow colour and metallic lustre, resembling gold. |
Marcasite | FeS₂ | orthorhombic | tabular, pyramidal, nodules, fibres, flakes, and masses. | Less stable, softer (5.5-6 on the Mohs scale), and lighter. | typically lighter in colour with a paler, more silvery appearance and a more brittle texture. |
Historical Background
Pyrite: Known as "fool's gold" due to its resemblance to gold. Used by ancient civilizations for starting fires and in jewellery. In the 16th and 17th centuries, it was mined for sulphur and iron. In the 19th and 20th centuries, it was used in the production of sulfuric acid.
Marcasite: Marcasite has been used since ancient times but not as extensively as pyrite. Its name comes from the Arabic word "markaschatsa," meaning "fire stone." Due to its instability and tendency to degrade, it was less favoured in historical applications.
Jewellery Suitability
Pyrite: Pyrite is sometimes used in jewellery due to its metallic lustre and attractive appearance. Its hardness makes it relatively durable for various jewellery applications. However, pyrite can tarnish and oxidize over time, requiring proper care. Some pyrite becomes unstable over time and literally falls to pieces, leaving a pile of dust in its place, especially where humidity and temperature changes occur. For this reason I personally would not use pyrite as jewellery, at least not expensive pieces.
Marcasite: Despite its similar appearance to pyrite, marcasite is not commonly used in jewellery. Marcasite is more brittle and prone to decay, making it unsuitable for long-term use in jewellery. What is often referred to as marcasite in jewellery is most probably pyrite due to its better stability and durability. My grandmother had a ring that she described as marcasite, antique jewellery was commonly set with onyx and “marcasite” that was most likely pyrite (below). I came across an old packet of material labelled “marcasite” as shown in the photos.
Metaphysical Properties
Pyrite: Believed to shield against negative energies and physical danger, used commonly for EMF protection. Associated with wealth and prosperity, often used in rituals for attracting money. Said to enhance physical stamina, energy, and vitality. Thought to boost self-confidence and assertiveness.
Marcasite: Linked to aiding personal and spiritual transformation. Believed to provide mental clarity and insight. Said to assist in healing emotional wounds and traumas. Like pyrite, it is also considered protective, but its instability in physical form reflects its role in confronting and transforming negative energies.
Conclusion
While pyrite and marcasite may look similar, their differences in structure, stability, and suitability for jewellery use set them apart. Pyrite's slightly better durability and attractive appearance make it a possible choice in jewellery, whereas marcasite's brittleness and tendency to degrade limit its use. Both minerals hold significant historical value and are esteemed in the metaphysical community for their unique properties. Whether you are a collector, a jewellery enthusiast, or someone interested in the metaphysical aspects of minerals, understanding the distinctions between pyrite and marcasite can enhance your appreciation of these fascinating iron sulphides.
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