Got a photo? Identify rocks instantly with the Rockby app
Open the appDescription
Stibnite with Quartz refers to an assemblage where the mineral stibnite (antimony sulfide) is found in close association with quartz (silicon dioxide). Stibnite typically occurs as elongated, acicular, or bladed crystals, often forming radiating aggregates or parallel bundles. It has a distinctive metallic luster and a lead-gray to steel-gray color, which can tarnish to iridescent hues. Quartz, in this association, usually forms as crystalline masses, euhedral crystals (often prismatic with pyramidal terminations), or as a gangue mineral filling the vein. The contrast between the metallic, often dark stibnite and the vitreous, typically lighter quartz makes for visually striking specimens. The presence of quartz provides a stable matrix for the often fragile stibnite crystals.
How to Identify
- Color
- Stibnite: Lead-gray to steel-gray, often tarnishing to iridescent blue or black. Quartz: Colorless, white, gray, or smoky.
- Luster
- Stibnite: Metallic to submetallic. Quartz: Vitreous (glassy).
- Texture
- Stibnite: Typically forms elongated, acicular, or bladed crystals, often in radiating or parallel aggregates. Can be massive. Quartz: Crystalline, granular, or massive.
- Crystal Form
- Stibnite: Orthorhombic, typically as prismatic, acicular, or bladed crystals, often striated parallel to the c-axis. Quartz: Hexagonal, typically as prismatic crystals with pyramidal terminations, or massive.
- Cleavage
- Stibnite: Perfect cleavage parallel to {010}, leading to easy splitting into thin, flexible blades. Quartz: No true cleavage, conchoidal fracture.
- Geological Environment
- Hydrothermal veins, hot spring deposits, and replacement deposits, often associated with volcanic or metamorphic terrains. Found in low-temperature to moderate-temperature environments.
Key Facts
- Hardness: Stibnite: 2-2.5 (Mohs); Quartz: 7 (Mohs)
- Specific Gravity: Stibnite: 4.52-4.62; Quartz: 2.65
- Crystal System: Stibnite: Orthorhombic; Quartz: Trigonal (often appears hexagonal)
- Color: Stibnite: Lead-gray to steel-gray, tarnishes iridescent; Quartz: Colorless, white, gray, smoky
- Luster: Stibnite: Metallic to submetallic; Quartz: Vitreous
- Transparency: Stibnite: Opaque; Quartz: Transparent to translucent
- Fracture: Stibnite: Subconchoidal to uneven; Quartz: Conchoidal
- Cleavage: Stibnite: Perfect on {010}; Quartz: None
- Composition: Stibnite: Antimony sulfide (Sb2S3); Quartz: Silicon dioxide (SiO2)
Quick Check
- Color: Stibnite: Lead-gray to steel-gray; Quartz: Colorless to white/gray
- Luster: Stibnite: Metallic; Quartz: Vitreous
- Streak: Stibnite: Grayish-black; Quartz: White
Physical Characteristics
- Crystal Habit: Stibnite: Acicular, bladed, prismatic, often in radiating or parallel aggregates, massive. Quartz: Prismatic, massive, granular.
- Cleavage Type: Stibnite: Perfect {010}; Quartz: None
- Fracture Type: Stibnite: Subconchoidal to uneven; Quartz: Conchoidal
- Tenacity: Stibnite: Sectile, brittle, flexible in thin laminae; Quartz: Brittle
- Luster Type: Stibnite: Metallic to submetallic; Quartz: Vitreous
Formation
Stibnite with Quartz forms primarily in low-temperature to moderate-temperature hydrothermal veins. These veins are typically found in areas of past or present volcanic activity, or in regions affected by regional metamorphism and associated fluid flow. The stibnite precipitates from antimony-rich hydrothermal solutions, often in association with silica-rich fluids that deposit quartz. The presence of quartz indicates a silica-saturated environment, which is common in many hydrothermal systems. The deposition often occurs in open spaces within faults, fractures, and shear zones.
Usage
Historically, stibnite was the primary ore of antimony, which is used in flame retardants, lead-acid batteries, semiconductors, and as an alloying agent to harden lead and tin. Quartz, while abundant, can be used as an abrasive, in glass manufacturing, and as a piezoelectric material. Specimens of stibnite with well-formed crystals in a quartz matrix are highly prized by mineral collectors.
Age Distribution
Typically associated with epithermal to mesothermal hydrothermal vein deposits, which can range from Cenozoic to Precambrian in age, depending on the specific geological setting.
Where to Find
Ichinokawa Mine, Shikoku, Japan
Historically famous for producing some of the world's finest and largest stibnite crystals, often in a quartz matrix.
Xikuangshan Mine, Hunan Province, China
The largest antimony deposit in the world, producing significant quantities of stibnite, often with quartz.
Baia Sprie (Felsöbánya), Maramureș County, Romania
Known for excellent stibnite specimens, frequently associated with quartz and other sulfides.
Pernek, Malacky District, Bratislava Region, Slovakia
Another classic European locality for stibnite, often found with quartz.
Murchison Range, Limpopo Province, South Africa
A major antimony-gold deposit where stibnite occurs, often with quartz.
Finding Tips
Look for Hydrothermal Veins
Stibnite with Quartz is typically found in hydrothermal vein deposits. Search for areas with evidence of past fluid flow, such as quartz veins, altered host rocks, and fault zones.
Identify Associated Minerals
Stibnite often co-occurs with other sulfide minerals (e.g., pyrite, arsenopyrite, cinnabar), gold, and various gangue minerals like calcite and barite. The presence of these minerals can indicate a favorable environment.
Observe Crystal Habit
Look for the distinctive elongated, acicular, or bladed crystals of stibnite, often radiating from a central point or forming parallel bundles within a quartz matrix. The metallic luster of stibnite is also a key indicator.
Exercise Caution
Stibnite contains antimony, which is toxic. Always handle specimens with gloves and wash hands thoroughly after handling. Avoid inhaling dust. Do not ingest. Store specimens in a secure, well-ventilated area, preferably in sealed containers to prevent dust dispersal.
Check for Softness and Cleavage
Stibnite is relatively soft (Mohs 2-2.5) and has perfect cleavage, meaning it can be easily scratched and will break into thin, flexible blades. Quartz, in contrast, is much harder (Mohs 7) and lacks cleavage.
Similar Rocks
Galena with Quartz
Galena (PbS) with Quartz (SiO2)
Also known as: Lead Glance with Quartz
Arsenopyrite with Quartz
Arsenopyrite (FeAsS) with Quartz (SiO2)
Also known as: Mispickel with Quartz
Bismuthinite with Quartz
Bismuthinite (Bi2S3) with Quartz (SiO2)
Also known as: Bismuth Glance with Quartz
Scientific Classification
- Mineral Class
- Stibnite: Sulfides; Quartz: Silicates (Tectosilicates)
- Group
- Stibnite: Stibnite Group; Quartz: Quartz Group
- Crystal System
- Stibnite: Orthorhombic; Quartz: Trigonal
- Chemical Formula
- Stibnite: Sb2S3; Quartz: SiO2
- Composition
- Stibnite: Antimony (71.69%) and Sulfur (28.31%); Quartz: Silicon (46.74%) and Oxygen (53.26%)
Explore Stibnite with Quartz
Identify rocks anywhere
Free on iOS, Android, and Web. Photo identification, full database, and your personal collection.