Got a photo? Identify rocks instantly with the Rockby app
Open the appDescription
Stibnite is an antimony sulfide mineral with the chemical formula Sb2S3. It is characterized by its distinctive metallic luster, lead-gray to silvery-white color, and often occurs in elongated, needle-like, or bladed crystals. It is a soft and brittle mineral with a perfect cleavage, making it quite fragile. Stibnite is the most important ore mineral of antimony.
How to Identify
- Color
- Lead-gray to silvery-white, often tarnishing to iridescent blue or black.
- Luster
- Bright metallic, sometimes dull on tarnished surfaces.
- Texture
- Often occurs in aggregates of acicular (needle-like), bladed, or columnar crystals. Can also be massive.
- Crystal Form
- Orthorhombic system, typically forming elongated, prismatic crystals with striations parallel to the c-axis. Crystals can be bent or curved.
- Cleavage
- Perfect cleavage parallel to the length of the crystals ({010}), leading to easy breakage into splinters.
- Geological Environment
- Low-temperature hydrothermal veins, hot spring deposits, and replacement deposits. Associated with quartz, calcite, barite, cinnabar, realgar, orpiment, and other sulfide minerals.
Key Facts
- Hardness: 2 on the Mohs scale (very soft, can be scratched by a fingernail)
- Specific Gravity: 4.52 - 4.62 (relatively heavy for a non-metallic mineral)
- Crystal System: Orthorhombic
- Color: Lead-gray to silvery-white, tarnishing to iridescent blue or black
- Luster: Metallic
- Transparency: Opaque
- Fracture: Uneven to subconchoidal
- Cleavage: Perfect on {010} (parallel to the length of the crystals)
- Composition: Antimony sulfide (Sb2S3)
Quick Check
- Color: Lead-gray to silvery-white
- Luster: Metallic
- Streak: Lead-gray to black
Physical Characteristics
- Crystal Habit: Acicular, bladed, columnar, prismatic, massive, radiating aggregates. Crystals are often striated parallel to the c-axis and can be bent or curved.
- Cleavage Type: Perfect in one direction ({010}), leading to easy splitting into fibrous or splintery fragments.
- Fracture Type: Uneven to subconchoidal, but rarely observed due to perfect cleavage.
- Tenacity: Sectile (can be cut with a knife) and brittle.
- Luster Type: Metallic, sometimes dull on tarnished surfaces.
Formation
Stibnite typically forms in low-temperature hydrothermal veins, often associated with hot springs and volcanic activity. It can also be found in replacement deposits and, less commonly, in contact metamorphic deposits. The mineral precipitates from hydrothermal solutions rich in antimony and sulfur, often in association with other sulfide minerals like cinnabar, realgar, orpiment, and pyrite, as well as quartz, calcite, and barite.
Usage
Historically, stibnite was used as a cosmetic (kohl) in ancient times. Today, its primary use is as the chief ore of antimony. Antimony is a metalloid used in various alloys to increase hardness and strength (e.g., in lead-acid batteries, bullet alloys, and bearing metals). It is also used in flame retardants, semiconductors, ceramics, glass, and as a pigment.
Age Distribution
Stibnite forms in various geological settings and is not restricted to a specific geological age. Its formation is tied to hydrothermal activity, which has occurred throughout Earth's history.
Where to Find
Xikuangshan Mine, Hunan Province, China
Historically the world's largest antimony mine and a prolific source of large, well-formed stibnite crystals.
Ichinokawa Mine, Ehime Prefecture, Japan
Famous for producing some of the finest and largest stibnite crystals, often exceeding 30 cm in length.
Baia Sprie (Felsöbánya), Maramureș County, Romania
Known for excellent stibnite specimens, often associated with other sulfide minerals.
Mali Idos Mine, Macedonia
A significant source of stibnite, often found in large, radiating aggregates.
Various localities in Bolivia, Peru, and Mexico
South and Central America have numerous deposits where stibnite is found, often in epithermal vein systems.
Finding Tips
Look for Hydrothermal Veins
Stibnite is primarily found in hydrothermal vein deposits. Search for areas with evidence of past hot spring activity, fault zones, or volcanic regions.
Associated Minerals
Stibnite often occurs with quartz, calcite, barite, cinnabar, realgar, orpiment, and other sulfide minerals. The presence of these minerals can indicate a potential stibnite deposit.
Crystal Habit
Keep an eye out for distinctive elongated, needle-like, or bladed metallic-gray crystals. These are characteristic of stibnite.
Safety Precautions
Stibnite contains antimony, which is toxic. Always handle stibnite with gloves and wash hands thoroughly after handling. Avoid inhaling dust from broken specimens. Do not ingest or allow contact with food or drink. Store specimens in a sealed container away from children and pets.
Similar Rocks
Galena
Galena (PbS)
Also known as: Lead Glance
Bismuthinite
Bismuthinite (Bi2S3)
Also known as: Bismuth Glance
Arsenopyrite
Arsenopyrite (FeAsS)
Also known as: Mispickel
Scientific Classification
- Mineral Class
- Sulfides
- Group
- Stibnite Group
- Crystal System
- Orthorhombic
- Chemical Formula
- Sb2S3
- Composition
- Antimony (Sb) 71.69%, Sulfur (S) 28.31%
Explore Stibnite
Identify rocks anywhere
Free on iOS, Android, and Web. Photo identification, full database, and your personal collection.