Pyrite Sun
Pyrite · Mineral Specimen
Crystal System
Cubic crystal system with flattened, discoidal habit and radial-fibrous structure
Mineral Group
Sulfides
Chemical Formula
FeS2
Formation Process
Sedimentary, forming in organic-rich shales and coal beds under low-oxygen, reducing conditions through bacterial sulfate reduction and iron precipitation
About This Crystal
A flattened, disk-shaped mineral aggregate commonly known as a pyrite sun or pyrite dollar, displaying a brassy-yellow metallic luster, radiating fibrous texture from a central point, and an opaque, metallic appearance
Physical Characteristics
Brass-yellow to pale bronze color, greenish-black to brownish-black streak, cubic habits flattened into disks, indistinct cleavage, uneven to conchoidal fracture, specific gravity around 4.8 to 5.0, brittle tenacity, metallic luster
Optical Properties
Opaque with a high metallic reflectance, isotropic in reflected light, strong bireflectance and strong anisotropy under cross-polarized light in polished sections
Hardness & Durability
Origin Region
Illinois, USA (specifically Sparta coal mines), and various international shale deposits
Hardness & Durability
Mohs hardness of 6 to 6.5, brittle toughness, sensitive to moisture and humidity which can lead to oxidation and pyrite decay (acid production), relatively poor wearability for delicate jewelry
Care & Maintenance
Store in a dry environment with low humidity to prevent oxidation and moisture-induced degradation, clean gently with a dry brush, avoid water and chemical cleaners
Rarity & Value
Uncommon to rare depending on size and perfection of the disk, valued by mineral collectors, prices range from moderate to high based on preservation and size
Special Characteristics
Distinctive radiating sunburst or discoidal habit formed within confining shale layers, strong metallic luster, potential to undergo oxidation known as pyrite decay if exposed to humidity
Lore & History
Used traditionally as a talisman for vitality, willpower, and abundance, often associated with the solar plexus chakra, appreciated historically as a fascinating geological curiosity known as coal mine fossils or pyrite dollars