Galena
Galena (Lead Sulfide) · Collector Mineral and Industrial Mineral (Primary ore of lead).
Crystal System
Cubic (Isometric) system. Typically occurs as cubes or octahedrons and as massive, granular, or fibrous aggregates; exhibits perfect cubic cleavage in three directions.
Mineral Group
Sulfides (Galena Group)
Chemical Formula
PbS (Lead Sulfide), often containing silver (Ag), zinc (Zn), or antimony (Sb) as trace impurities.
Formation Process
Hydrothermal mineral formed at low to intermediate temperatures in veins where sulfur and lead precipitate from solution. Also occurs in contact metamorphic zones and sedimentary rocks as replacement deposits.
About This Crystal
The specimen shows a lead-gray metallic luster with a distinctively heavy, dense appearance. It features fractured surfaces showcasing the characteristic cubic cleavage. The color is silver-gray to bluish-gray, and the luster is bright metallic on fresh surfaces, which can dull to a leaden-gray after exposure.
Physical Characteristics
Color: Lead gray; Streak: Lead gray; Cleavage: Perfect cubic {001}; Fracture: Subconchoidal to uneven; Specific Gravity: 7.2–7.6 (extremely heavy); Tenacity: Brittle; Fluorescence: Generally none.
Optical Properties
Opaque (not transparent); Metallic luster. It is isotropic under reflected light, though silver-rich varieties may show slight anomalous anisotropy.
Hardness & Durability
Origin Region
Notable sources include Missouri and Kansas (USA), Derbyshire (UK), Mexico, and Morocco. Formed in hydrothermal veins and carbonate-hosted replacement deposits.
Hardness & Durability
Mohs hardness: 2.5–2.75. Very soft and easy to scratch. Brittle toughness. Low wearability due to softness and high toxicity; strictly for collection/display.
Care & Maintenance
Wash hands after handling due to lead content. Avoid ingestion or inhalation of dust. Clean with a dry cloth or warm soapy water only if necessary; avoid ultrasonic cleaners and chemicals. Keep away from harder stones to prevent scratching.
Rarity & Value
Very common mineral. Value is generally low for mass-produced ore but increases significantly for well-formed cubic crystals or 'specimen-grade' matrix pieces. Untreated normally.
Special Characteristics
Highly recognized for its extreme density (high specific gravity) and its ability to split into perfect cubes when struck. It is also often argentiferous (silver-bearing).
Lore & History
Historically used as an ancient cosmetic (Kohl) in Egypt and as a primary lead source for bullets, piping, and glass. Traditionally associated with 'grounding' in metaphysical practices due to its heavy weight, though modern focus is strictly on its chemical nature as a lead ore.