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Native antimony is a rare mineral consisting of the element antimony (Sb) in its uncombined, metallic form. It is a semi-metal or metalloid, exhibiting properties intermediate between metals and nonmetals. It typically occurs as granular masses, lamellar aggregates, or less commonly, as distinct rhombohedral crystals. Its metallic luster and tin-white to steel-gray color are characteristic. It is brittle and has perfect basal cleavage.
How to Identify
- Color
- Tin-white to steel-gray, often tarnishing to dull gray or black.
- Luster
- Metallic, sometimes dull on tarnished surfaces.
- Texture
- Granular, massive, lamellar, or rarely as distinct rhombohedral crystals.
- Crystal Form
- Typically massive or granular. When crystallized, it forms rhombohedral crystals, often distorted or tabular.
- Cleavage
- Perfect basal cleavage on {0001}.
- Geological Environment
- Low-temperature hydrothermal veins, often associated with stibnite, arsenopyrite, sphalerite, galena, pyrite, quartz, and calcite. Also found in some pegmatites and as a secondary mineral in oxidized zones of antimony deposits.
Key Facts
- Hardness: 3-3.5 on the Mohs scale
- Specific Gravity: 6.61-6.72
- Crystal System: Trigonal
- Color: Tin-white to steel-gray, tarnishing to dull gray or black
- Luster: Metallic
- Transparency: Opaque
- Fracture: Uneven to subconchoidal
- Cleavage: Perfect basal on {0001}
- Composition: Elemental Antimony (Sb)
Quick Check
- Color: Tin-white to steel-gray
- Luster: Metallic
- Streak: Gray to black
Physical Characteristics
- Crystal Habit: Massive, granular, lamellar, rarely rhombohedral crystals
- Cleavage Type: Perfect basal
- Fracture Type: Uneven to subconchoidal
- Tenacity: Brittle
- Luster Type: Metallic
Formation
Native antimony forms under reducing conditions, often in low-temperature hydrothermal veins, sometimes in association with other antimony minerals like stibnite, or with arsenic, silver, and gold ores. It can also occur as a primary mineral in some pegmatites or as a secondary mineral in oxidized zones of antimony deposits.
Usage
Native antimony itself is not a primary ore for industrial antimony production due to its rarity. However, antimony as an element is crucial. It is used as an alloying agent to harden lead and tin, particularly in batteries, solders, and bullet alloys. Antimony compounds are used in flame retardants, ceramics, glass, and semiconductors. Historically, it was used in cosmetics and medicine.
Age Distribution
Found in various geological ages, typically associated with hydrothermal vein deposits.
Where to Find
Wolfsberg, Harz, Germany
Historically significant locality for well-formed native antimony crystals.
Sala, Västmanland, Sweden
Known for native antimony occurrences in silver-lead-zinc deposits.
Lengenbach, Binn Valley, Valais, Switzerland
Found in polymetallic sulfide deposits.
New Brunswick, Canada
Occurrences reported in various polymetallic vein deposits.
Japan
Several localities, including Ichinokawa, Shikoku, known for stibnite, where native antimony can also occur.
Finding Tips
Associated Minerals
Look for native antimony in areas known for stibnite (antimony sulfide), arsenopyrite, sphalerite, galena, and gold-silver mineralization in quartz veins.
Hydrothermal Veins
Focus on low-temperature hydrothermal vein systems, particularly those cutting through metamorphic or igneous rocks.
Color and Luster
Its distinctive tin-white to steel-gray color and metallic luster, even when tarnished, are key identifiers. Freshly broken surfaces will show the bright metallic sheen.
Brittleness
Test its brittleness; it will easily break or crumble, unlike malleable native metals.
Safety Precautions
Antimony and its compounds are toxic. Avoid inhaling dust when handling, especially when breaking samples. Always wash hands thoroughly after handling. Do not ingest. Use appropriate personal protective equipment (PPE) such as gloves and eye protection, especially when collecting or preparing specimens.
Similar Rocks
Arsenic
Arsenic
Also known as: Native Arsenic (As)
Bismuth
Bismuth
Also known as: Native Bismuth (Bi)
Stibnite
Stibnite
Also known as: Antimony Sulfide (Sb2S3)
Scientific Classification
- Mineral Class
- Native Elements
- Group
- Arsenic Group
- Crystal System
- Trigonal
- Chemical Formula
- Sb
- Composition
- Antimony
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