Gemstone profile and identification guide
Agate
Agate is a banded chalcedony variety of quartz identified by concentric or parallel growth bands and waxy lustre.
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Overview
Agate is a banded chalcedony variety of quartz identified by concentric or parallel growth bands and waxy lustre.
Did you know? Historic agate cutting centers include Idar-Oberstein, which processed large volumes of Brazilian rough.
Use this profile as a collector reference and educational guide for quick on-page comparison, then validate with the interactive identification system.
Identification
Name: Agate
Scientific classification: Silicate (Chalcedony Quartz)
Hardness: 7 Mohs
Transparency: translucent
Lustre: waxy
Crystal system: Trigonal (microcrystalline aggregate)
Primary colour: Grey
Secondary colour: White
Colour family: Greys
Identification is based on chalcedony texture, curved or parallel banding, Mohs 7 hardness, and waxy lustre.
Verification Status
Status: verified-core-fields
Reference priority: GIA, Gem-A, Mindat, International Gem Society
Core identity, locality, and physical-property fields reviewed against standard gemological references.
Values are given as practical gemological ranges where appropriate.
Physical Properties
Hardness category: hard
Hardness value: 7 Mohs
Chemical composition: Silicon dioxide (SiO2)
Crystal system: Trigonal (microcrystalline aggregate)
Common locations: Brazil (Rio Grande do Sul), Uruguay (Artigas), India, Mexico, Botswana, Madagascar
Learn more: Gem-A gemstone education resources.
Colour Variations
Banded chalcedony in white, grey, blue, brown, red, yellow, and black combinations.
Optical effects: Banded Structure
Detailed Gemology
Mineral species: Quartz (chalcedony variety)
Mineral group: Quartz group
Chemical formula: Silicon dioxide (SiO2)
Mohs hardness: 7
Crystal system: Trigonal (microcrystalline aggregate)
Lustre: waxy
Transparency: translucent
Streak: White
Cleavage: None
Fracture: Conchoidal to uneven
Specific gravity: 2.58-2.64
Refractive index: 1.53-1.54
Optical phenomena: Banded structure
Colour range: White, grey, blue, brown, red, yellow, black
Common inclusions: Iron-oxide staining, manganese dendrites, tubular structures
Geological environment: Silica-rich fluids in volcanic and sedimentary host rocks
Principal mining regions: Brazil (Rio Grande do Sul), Uruguay (Artigas), India, Mexico, Botswana, Madagascar
Important commercial sources: Major commercial agate comes from Brazil and Uruguay, with additional production in India, Mexico, Botswana, and Madagascar
Historical significance: Widely used for seals, cameos, and ornamental carving since antiquity.
Common treatments: Dyeing, heating, and sugar-acid blackening are common.
Synthetic or imitation forms: Dyed chalcedony and glass imitations are common; true synthetic banded agate is uncommon.
Common look-alikes: Jasper, dyed chalcedony, banded calcite
Jewellery uses: Used in cabochons, beads, carvings, and decorative objects where banding is the main visual feature.
Care recommendations: Mohs 7 allows routine wear. Clean with mild soap and water; avoid prolonged ultrasonic cleaning for fractured or dyed material.
Cross-check profile data with GIA Gem Encyclopedia and Mindat entry for Agate.
Formation
Forms by rhythmic silica deposition in cavities and fractures of volcanic rocks, commonly producing banded chalcedony layers.
Origin
Major commercial agate comes from Brazil and Uruguay, with additional production in India, Mexico, Botswana, and Madagascar
Uses
Best for: Used in cabochons, beads, carvings, and decorative objects where banding is the main visual feature.
Ideal uses: Cabochons, beads, carvings, and inlay work rather than high-dispersion faceted jewellery.
Care
Mohs 7 allows routine wear. Clean with mild soap and water; avoid prolonged ultrasonic cleaning for fractured or dyed material.
Need another candidate? Use advanced gemstone search or return to the identification guide.
Related gemstones by colour
Related gemstones by hardness
Gemstones from the same mineral family
Commonly confused gemstones
Agate FAQ
How can I identify Agate?
Compare hardness (7 Mohs), crystal system (Trigonal (microcrystalline aggregate)), colour profile, and lustre (waxy) with your sample. Then cross-check related gemstones listed above.
What colour range does Agate appear in?
Banded chalcedony in white, grey, blue, brown, red, yellow, and black combinations.
Where is Agate commonly used?
Cabochons, beads, carvings, and inlay work rather than high-dispersion faceted jewellery.. For maintenance, follow the care guidance in this profile.
Scientific References
GIA: general gemstone identity (reviewed) - Batch 01 factual verification pass.
Gem-A: gemological terminology and testing references (reviewed) - Batch 01 factual verification pass.
Mindat: mineral species and principal localities (reviewed) - Batch 01 factual verification pass.
International Gem Society: gem trade context and treatment overview (reviewed) - Batch 01 factual verification pass.