Galena
Lead Sulfide · Mineral Specimen / Industrial Mineral
Crystal System
Cubic (Isometric); commonly occurs in cubic, octahedral, or massive granular forms with perfect cubic cleavage.
Mineral Group
Sulfides
Chemical Formula
PbS (Lead Sulfide), often containing trace Silver (Ag)
Formation Process
Hydrothermal; typically precipitates from low to medium-temperature mineralized fluids in veins or as replacement deposits in limestone and dolostone.
About This Crystal
A heavy, lead-gray mineral with a brilliant metallic luster that may tarnish to a dull gray over time. It is opaque with a distinctive cubic structure.
Physical Characteristics
Color: Lead-gray; Streak: Lead-gray; Luster: Metallic; Cleavage: Perfect cubic (three directions at 90 degrees); Specific Gravity: 7.2–7.6 (very dense); Tenacity: Brittle.
Optical Properties
Opaque; metallic luster provides high reflectivity. It does not exhibit pleochroism or birefringence as it is isotropic (cubic).
Hardness & Durability
Origin Region
Notable sources include Missouri (USA), Mexico, Germany, Peru, and the United Kingdom. Formed in hydrothermal veins and replacement deposits.
Hardness & Durability
Mohs Hardness: 2.5 - 2.75. Very soft and brittle; easily scratched by a penny and prone to fracturing along cleavage planes.
Care & Maintenance
Handle with gloves due to lead content; avoid inhalation of dust. Clean with dry cloth or warm soapy water only. Store separately from harder minerals to prevent scratching.
Rarity & Value
Very common; value is generally low for massive specimens but higher for well-terminated cubic or octahedral crystals. Primary ore of lead.
Special Characteristics
Exceptional cubic cleavage; high density; semiconducting properties (historically used in crystal radio detectors). Not fluorescent.
Lore & History
Historically used in Ancient Egypt as kohl (eyeliner) and as a major source of silver. In traditional lore, it is considered a 'grounding' stone that provides stability.