Got a photo? Identify rocks instantly with the Rockby app
Open the appDescription
Galena is a lead sulfide mineral, PbS, and is the most important ore of lead. It is characterized by its distinctive metallic luster, high density, and perfect cubic cleavage. Its silvery-gray color often tarnishes to a dull gray. Galena is a common and widespread mineral, found in various geological settings.
How to Identify
- Color
- Lead-gray to silvery-gray, often tarnishing to a dull gray or iridescent blue/purple.
- Luster
- Bright metallic luster on fresh surfaces, becoming duller with tarnish.
- Texture
- Typically massive, granular, or as well-formed cubic, cubo-octahedral, or octahedral crystals.
- Crystal Form
- Cubic, cubo-octahedral, or octahedral crystals are common. Also found as massive, granular, or fibrous aggregates.
- Cleavage
- Perfect cubic cleavage in three directions at 90 degrees, producing characteristic step-like fractures or perfect cubes when broken.
- Geological Environment
- Hydrothermal veins (mesothermal to epithermal), Mississippi Valley-type (MVT) deposits, skarns, and replacement deposits in sedimentary rocks (e.g., limestones).
Key Facts
- Hardness: 2.5-2.75 on the Mohs scale (relatively soft)
- Specific Gravity: 7.4-7.6 g/cm³ (very heavy)
- Crystal System: Isometric (cubic)
- Color: Lead-gray to silvery-gray, often tarnishing
- Luster: Metallic
- Transparency: Opaque
- Fracture: Subconchoidal to uneven, but rarely observed due to perfect cleavage
- Cleavage: Perfect cubic (three directions at 90 degrees)
- Composition: Lead sulfide (PbS), often with minor silver (Ag), bismuth (Bi), antimony (Sb), and zinc (Zn) impurities.
Quick Check
- Color: Lead-gray to silvery-gray
- Luster: Metallic
- Streak: Lead-gray to black
Physical Characteristics
- Crystal Habit: Cubic, cubo-octahedral, octahedral; also massive, granular, or fibrous.
- Cleavage Type: Perfect cubic {001}
- Fracture Type: Subconchoidal to uneven (rarely seen due to cleavage)
- Tenacity: Brittle
- Luster Type: Metallic
Formation
Galena typically forms in hydrothermal veins, often in association with sphalerite, pyrite, chalcopyrite, quartz, calcite, and fluorite. It can also occur in sedimentary rocks as replacement deposits, in skarns, and in some metamorphic rocks.
Usage
Galena is the primary ore of lead (Pb). Lead is used in batteries, ammunition, radiation shielding, and historically in plumbing and pigments. It is also a significant source of silver (Ag) as a byproduct, as silver often substitutes for lead in the galena crystal lattice.
Age Distribution
Found in geological formations of various ages, from Precambrian to Cenozoic, often associated with hydrothermal activity.
Where to Find
Tri-State District, USA
Historically a major producer of lead and zinc, encompassing parts of Missouri, Kansas, and Oklahoma. Known for large MVT deposits.
Broken Hill, Australia
One of the world's largest lead-zinc-silver deposits, known for massive galena occurrences.
Freiberg, Germany
A classic locality for well-crystallized galena and other sulfide minerals from hydrothermal veins.
Cœur d'Alene District, Idaho, USA
Famous for its silver-lead-zinc deposits, with significant galena mineralization.
Potosí, Bolivia
Historically renowned for its vast silver deposits, where galena was a primary ore mineral.
Finding Tips
Look for Associated Minerals
Galena is frequently found with sphalerite (zinc sulfide), pyrite (iron sulfide), chalcopyrite (copper iron sulfide), quartz, calcite, and fluorite. Identifying these associated minerals can help locate galena.
Check for High Density
Galena is notably heavy for its size due to its lead content. This high specific gravity (7.4-7.6 g/cm³) is a key diagnostic feature.
Observe Cleavage
The perfect cubic cleavage is very distinctive. Broken pieces will often show stair-step fractures or break into smaller cubes.
Test for Streak
Galena produces a characteristic lead-gray to black streak on an unglazed porcelain plate.
Safety Precautions
Galena contains lead, which is toxic. Always wash hands thoroughly after handling. Avoid inhaling dust if breaking samples. Do not ingest. Store samples safely away from children and pets. Prolonged exposure to lead can cause serious health problems.
Similar Rocks
Argentite
Ag2S
Also known as: Silver glance
Molybdenite
MoS2
Also known as: Moly
Graphite
C
Also known as: Black lead
Scientific Classification
- Mineral Class
- Sulfides
- Group
- Galena Group
- Crystal System
- Isometric (Cubic)
- Chemical Formula
- PbS
- Composition
- Lead sulfide (86.6% lead, 13.4% sulfur by weight)
Explore Galena
Identify rocks anywhere
Free on iOS, Android, and Web. Photo identification, full database, and your personal collection.