Gemstone profile and identification guide
Zoisite
Zoisite is an orthorhombic sorosilicate species encompassing several gem varieties.
Profile Navigation
Overview
Zoisite is an orthorhombic sorosilicate species encompassing several gem varieties.
Did you know? Tanzanite is the blue-violet gem variety of zoisite.
Use this profile as a collector reference and educational guide for quick on-page comparison, then validate with the interactive identification system.
Identification
Name: Zoisite
Scientific classification: Silicate (Epidote Group: Zoisite)
Hardness: 6.5 Mohs
Transparency: translucent
Lustre: vitreous
Crystal system: Orthorhombic
Primary colour: Green
Secondary colour: Blue
Colour family: Greens
Species-level testing distinguishes zoisite from look-alike green and blue gems.
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.
Final remaining profile set completed in targeted pass.
Physical Properties
Hardness category: hard
Hardness value: 6.5 Mohs
Chemical composition: Calcium aluminum hydroxyl sorosilicate [Ca2Al3(SiO4)(Si2O7)O(OH)]
Crystal system: Orthorhombic
Common locations: Tanzania, Austria, Norway, Kenya, Pakistan
Learn more: Gem-A gemstone education resources.
Colour Variations
Zoisite species with broad color range including famous varieties like tanzanite and thulite.
Optical effects: Pleochroism (variety-dependent)
Detailed Gemology
Mineral species: Zoisite
Mineral group: Epidote group
Chemical formula: Calcium aluminum hydroxyl sorosilicate [Ca2Al3(SiO4)(Si2O7)O(OH)]
Mohs hardness: 6.5
Crystal system: Orthorhombic
Lustre: vitreous
Transparency: translucent
Streak: White
Cleavage: Perfect in one direction
Fracture: Conchoidal to uneven
Specific gravity: 3.1-3.4
Refractive index: 1.69-1.70
Optical phenomena: None typically diagnostic
Colour range: Green, blue-violet, pink, gray depending on variety
Common inclusions: Species-dependent inclusions and growth features
Geological environment: Species-dependent
Principal mining regions: Tanzania, Austria, Norway, Kenya, Pakistan
Important commercial sources: Zoisite species occurs in metamorphic environments with multiple gem and ornamental varieties
Historical significance: Recognized in gemological and lapidary trade.
Common treatments: Treatment status varies by product; disclose when present.
Synthetic or imitation forms: Imitations may exist depending on species.
Common look-alikes: Species-dependent look-alikes.
Jewellery uses: Used in faceted gems (variety-dependent), cabochons, and collector specimens.
Care recommendations: Moderate durability; avoid harsh impact and thermal shock.
Cross-check profile data with GIA Gem Encyclopedia and Mindat entry for Zoisite.
Formation
Forms in metamorphic terrains and associated hydrothermal conditions.
Origin
Zoisite species occurs in metamorphic environments with multiple gem and ornamental varieties
Uses
Best for: Used in faceted gems (variety-dependent), cabochons, and collector specimens.
Ideal uses: Collector and variety-specific jewelry applications.
Care
Moderate durability; avoid harsh impact and thermal shock.
Need another candidate? Use advanced gemstone search or return to the identification guide.
Related gemstones by colour
Related gemstones by hardness
Commonly confused gemstones
Zoisite FAQ
How can I identify Zoisite?
Compare hardness (6.5 Mohs), crystal system (Orthorhombic), colour profile, and lustre (vitreous) with your sample. Then cross-check related gemstones listed above.
What colour range does Zoisite appear in?
Zoisite species with broad color range including famous varieties like tanzanite and thulite.
Where is Zoisite commonly used?
Collector and variety-specific jewelry applications.. For maintenance, follow the care guidance in this profile.
Scientific References
GIA: general gemstone identity (reviewed) - Batch 10 factual verification pass.
Gem-A: gemological terminology and testing references (reviewed) - Batch 10 factual verification pass.
Mindat: mineral species and principal localities (reviewed) - Batch 10 factual verification pass.
International Gem Society: gem trade context and treatment overview (reviewed) - Batch 10 factual verification pass.