Iron Pyrite
Pyrite · Mineral Specimen / Decorative Stone
Crystal System
Cubic (Isometric); habit can be cubic, octahedral, or pyritohedral; also occurs as granular or massive aggregates (as seen in the granular matrix shown).
Mineral Group
Sulfides
Chemical Formula
FeS2
Formation Process
Hydrothermal, magmatic segregation, or sedimentary (authigenic precipitation in anoxic environments). It forms across a wide range of temperatures and pressures.
About This Crystal
This specimen appears to be a massive or granular variety of Pyrite. It features a brassy-yellow to pale gold metallic luster. The surface is composed of tiny interlocking crystals that glimmer in the light. It is typically opaque with a dense, heavy feel for its size.
Physical Characteristics
Color: Brass-yellow; Streak: Greenish-black to brownish-black; Cleavage: Indistinct; Fracture: Conchoidal to uneven; Specific Gravity: 4.9–5.2; Tenacity: Brittle; Luster: Metallic.
Optical Properties
Opaque; isotropic (as it is cubic); exhibits no refractive index in the visible spectrum; highly reflective (metallic reflection).
Hardness & Durability
Origin Region
Found worldwide; notable sources include Spain (Rio Tinto), Peru (Huanzala), Italy (Elba), and various locations in the USA.
Hardness & Durability
Mohs hardness: 6–6.5; brittle and prone to fracturing; harder than gold (which is 2.5) but softer than quartz.
Care & Maintenance
Keep dry to prevent 'pyrite disease' (oxidation into sulfuric acid and iron sulfates); avoid high humidity, ultrasonic cleaners, and moisture. Clean with a dry brush.
Rarity & Value
Very common; value is generally low for massive forms but higher for perfectly formed cubic or pyritohedral crystals. Specimens are usually untreated.
Special Characteristics
Known as 'Fool's Gold' due to its color; emits sparks when struck against steel (striking fire); can sometimes contain trace amounts of gold or cobalt.
Lore & History
Used by humans for thousands of years to create fire. In lore, it is often associated with the solar plexus chakra, abundance, protection, and mental clarity. Ancient Incas used large slabs of pyrite as mirrors.