Galena
Galena (Lead Sulfide) · Mineral Specimen / Industrial Mineral
Crystal System
Cubic (Isometric); commonly occurs as cubes and octahedrons, often in massive or granular habits.
Mineral Group
Sulfides
Chemical Formula
PbS with common inclusions of Ag, Sb, As, Cu
Formation Process
Primarily Hydrothermal veins forming in intermediate to low temperatures; also found as contact metamorphic replacements and in sedimentary lead-zinc deposits.
About This Crystal
A dense, lead-gray mineral with a distinct bright metallic luster on fresh surfaces. The specimen appears as an opaque, granular, or massive matrix with a duller weathered exterior, showing small glittering facets in the cavity.
Physical Characteristics
Color: Lead gray; Streak: Lead gray; Cleavage: Perfect cubic (three directions at 90 degrees); Fracture: Subconchoidal or uneven; Specific Gravity: Approx. 7.4–7.6; Tenacity: Brittle; Fluorescence: Generally none.
Optical Properties
Opaque; Metallic luster; Refractive index is not applicable as it is non-transparent; exhibits no pleochroism due to cubic symmetry.
Hardness & Durability
Origin Region
Prominent sources include Missouri and Kansas (USA), Derbyshire (England), and silver-lead deposits in Australia and Mexico.
Hardness & Durability
Mohs hardness: 2.5–2.75 (can be scratched by a penny). Very brittle with high density, making it susceptible to impact damage.
Care & Maintenance
Handle with gloves as it is a primary lead ore and toxic if inhaled or ingested. Clean with a dry, soft brush; avoid acids which react to release hydrogen sulfide gas. Store in a stable, dry environment.
Rarity & Value
Very Common; widespread globally. Value is generally low for massive specimens but increases significantly for well-formed cubic crystals or 'argentiferous' (silver-bearing) varieties.
Special Characteristics
High density (very heavy for its size); perfect cubic cleavage allows it to break into tiny perfect cubes; often serves as a primary source of silver through inclusions.
Lore & History
Historically used for lead smelting since at least 3000 BC. In Ancient Egypt, it was ground into kohl for eye makeup. Traditionally associated with grounding and centering energies in folk belief, though its primary modern significance is scientific and industrial.