Marcasite Vs. Pyrite

Marcasite is a popular mineral composed of iron sulfide.^[1] Pyrite is a very popular gemstone (marcasite) and its chemical composition is also iron sulfide.^[2]

Quick Facts on Differences of Marcasite and Pyrite

For a quick recap of the differences marcasite and pyrite:

• While both marcasite and pyrite streaks black or green, marcasite streaks brown or dark brown and pyrite streaks black green.
• While both marcasite and pyrite can be commonly yellow, marcasite is often brown or white.
• Marcasite's rarity is more rare than pyrite.

Quick Facts on Similarities of Marcasite and Pyrite

The similarities of marcasite and pyrite include:

• Marcasite and pyrite both are opaque.
• For chemical formulas, marcasite and pyrite both are FeS2.
• In terms of luster, marcasite and pyrite both are metallic.
• Marcasite's specific gravity overlaps with pyrite - marcasite ranges from 4.85 to 4.92 and pyrite ranges from 4.9 to 5.2.

Summary of Marcasite

Marcasite is a mineral that is commonly found in sedimentary rocks, and it is a type of iron sulfide. It has a metallic luster, and it is often confused with pyrite, which is also an iron sulfide mineral. However, marcasite is less stable than pyrite and can easily oxidize and become discolored. It is also more brittle than pyrite and can easily break into small pieces.

Summary of Pyrite

Pyrite, also known as iron pyrite or fool's gold, is a mineral with a metallic luster and a brass-yellow color. It is composed of iron disulfide (FeS2) and is commonly found in sedimentary rocks, metamorphic rocks, and hydrothermal veins. Pyrite is often mistaken for gold due to its color and metallic appearance, but it is much less valuable than gold.

Table Comparison of Marcasite vs Pyrite