On this page
UnderstandWhat it is, what people ask, how far this page goes
Natural inorganic gem materials · Mineral species · Natural identity; treatment status unknown
Epidote
A silicate mineral species listed in GB/T 16552-2017 Appendix A.1; Epidote beads may be multi-mineral aggregates and must be identified piece by piece. This page compares how the major standards and institutions name it, what must be disclosed when selling it, whether it can be worn every day, how it is treated and identified, and which source each conclusion comes from.
Price, rarity and origin are outside the scope of this wiki.
What this page can answer
This page covers
- How Epidote forms and what gives its colourFormation setting, process and timescale; where its colour and optical effects come from, each finding graded and sourced
- How to identify EpidoteHow far lab testing can go and whether a synthetic exists
- Caring for and wearing EpidoteCleaning, heat, chemicals and light, as the cited sources give them; durability indicators and wearing advice
- Hardness, density and refractive index of EpidoteEach value with its source and check date
- Epidote in English, Chinese and Japanese; national standard namesNames in four languages, the GB/T standard name and the suggested listing name; and: Which of GIA, FTC, CIBJO and Gem-A have a name for it on record, and do those agree?
- Name origin and history of EpidoteWhere the name comes from
- Listing and disclosing EpidoteThe listing name to use; what must be disclosed before sale
- Standard clauses that define EpidoteWhich clause defines it, each cross-checked
What we cannot conclude
- Whether one particular bead is natural, treated or synthetic — only a laboratory report can settle that.
- Geographic origin, unless an origin report accompanies the item.
- Price, rarity or investment value: this wiki covers naming and disclosure only.
Material research: formation, causes and history
What authoritative sources say about how this material forms, what causes its colour and optical effects, where its name comes from and how people have used it. Each statement carries an evidence grade and its sources; it describes the material in general, not any specific piece.
How it forms
Epidote is a calcium aluminium sorosilicate of the epidote group. It is characteristic of several facies of regionally metamorphosed rocks (greenschist, epidote-hornfels and blueschist facies), and also occurs in contact zones between igneous rocks and calcareous sedimentary rocks; it can additionally form by alteration of plagioclase (saussuritization). Epidote forms a solid-solution series with clinozoisite, and its crystals are commonly prismatic and striated. GIA has also reported pink to red epidote microcrystals as 'firework' sprays included in rock crystal quartz.
Scope: Covers the origin, composition, occurrence and coloration of epidote as a natural calcium aluminium sorosilicate mineral species; does not address synthetic materials or gem variety naming.
Sources Handbook of Mineralogy · G&G Spring 2024
Where it forms
Regionally metamorphosed rocks (greenschist, epidote-hornfels and blueschist facies)
Sources Handbook of Mineralogy
Zones of contact separating igneous rocks from calcareous sedimentary rocks
Sources Handbook of Mineralogy
Sites of plagioclase alteration (saussuritization)
Sources Handbook of Mineralogy
How it forms, step by step
Calcium-aluminium bearing rocks recrystallize under regional or contact metamorphic conditions.
Sources Handbook of Mineralogy
Epidote crystallizes in several metamorphic facies (greenschist, epidote-hornfels and blueschist facies).
Sources Handbook of Mineralogy
Epidote may develop where igneous rocks are in contact with calcareous sedimentary rocks, or through the alteration of plagioclase.
Sources Handbook of Mineralogy
Epidote forms a solid-solution series with clinozoisite, with crystals commonly prismatic and striated.
Sources Handbook of Mineralogy
Link to appearance
Epidote is commonly pistachio-green (yellow-green) to pale green, also yellow to greenish black; the green is related to trivalent iron in its composition, while GIA's pink to red epidote is colored by manganese.
Sources Handbook of Mineralogy · G&G Spring 2024
Timescale
The sources state no absolute geological timescale for epidote formation.
Sources Handbook of Mineralogy · G&G Spring 2024
Supporting findings
Several facies of regionally metamorphosed rocks—greenschist, epidote-hornfels and blueschist—are characteristically epidote-bearing; the mineral also appears in contact zones separating igneous from calcareous sedimentary rocks, and can arise through plagioclase alteration.
Evidence grade BScope: Describes epidote's natural metamorphic and contact origin; not laboratory synthesis.
Sources Handbook of Mineralogy
Epidote is commonly associated with zeolites, amphiboles, plagioclase, quartz, actinolite and calcite (greenschist facies).
Evidence grade BScope: Describes epidote's typical associations; not all occurrences share the same assemblage.
Sources Handbook of Mineralogy
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
Europe
- Le Bourg-d'Oisans, Isère, France
Sources Mindat: Epidote
Seas and coasts
- WorldwideWidespread mineral
Sources Handbook of Mineralogy
These are localities recorded by authoritative sources, not an origin finding for any individual piece. The CIBJO Gemstone Book (2022, §4.2.3) says a place of origin names where a gem was mined or harvested, is a matter of opinion, does not imply a level of quality, and that cutting, processing or exporting centres must not be used to imply origin. See how far testing can go on this page, the origin determination guide and the overview of recorded localities.
Causes of colour and optical effects
The pink to red epidote microcrystals analyzed by GIA contain manganese, which caused their pink to red color (distinct from the ordinary dark brownish-green epidote, or the Mn-rich material loosely called piemontite).
Evidence grade AScope: Applies only to the pink-red epidote microcrystals in quartz reported by GIA; not all epidote is Mn-colored.
Sources G&G Spring 2024
Where the name comes from
Epidote's name is Greek, meaning "increase", a nod to the prism base that has one side longer than the other.
Evidence grade BScope: This states only the origin of the name and does not establish the material's composition, locality, natural origin, or whether it was treated.
Sources Handbook of Mineralogy
Other research findings
Epidote is a silicate containing Ca, Al and Fe3+, forms a solid-solution series with clinozoisite, and belongs to the epidote group.
Evidence grade BScope: Describes epidote's composition and group relation; does not extend to gem grading.
Sources Handbook of Mineralogy
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- The sources state no absolute geological timescale for epidote formation.
- GIA's pink-red epidote is a single-case report; its Mn content and coloring mechanism are not quantified in the source.
Methodology
- Origin determination and its limits
- Quality grading and value factors
- How gemmology became a technical discipline
Evidence grades
- A
- Standards bodies, government geological surveys, peer-reviewed research and museum records
- B
- Institutional educational material
- C
- Specialist databases or cautious readings
A statement is never graded above its strongest source.
This section is LumaLark's own factual restatement of public authoritative sources, credited item by item; it contains no verbatim excerpts, images or third-party logos.
DecideListing name, disclosure, care and treatments
- Suggested listing name
- Epidote
GB/T 16552—2017 Table A.1 “Epidote” · IMA Mineral List 2026-07 “Epidote”
Construction or treatment status
Natural identity; treatment status unknown
Related:Disclosure and cautions
This page cannot answer
Natural? · Origin · Price
A lab report settles these; this wiki covers naming and disclosure.
Related:What this page can answer
Answer at a glance
Epidote is Epidote; use "Epidote" for listings, and disclose any known treatments.
Evidence
- GB/T · Table A.1, row 绿帘石 (Epidote)
What this means for you
Before buying, check the recommended listing name "Epidote" and any disclosed treatments on this page, and ask the seller for a grading report if in doubt.
Known uncertainty
- Last reviewed
- 2026-09-01
Care and wear
Normal care for every gemstone (CIBJO Gemstone Book §6.1), in brief:
- Handle it gently.
- Store pieces apart when not worn, so they cannot scratch each other.
- Clean with warm soapy water and a soft brush.
- Use ultrasonic cleaners only with caution.
The §6.1 wording and the full list of §6.2 special-care letters cited on this page are on the general gem care page.
Care
Epidote — care (cleaning): Some stones are susceptible to damage from ultrasonic cleaning. Do not expose them to ultrasonic cleaning.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code j
- Treatment state
- any treatment state
Source & check 2026-09-25
- Source
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) (CIBJO): §8 Annex C, Epidote, p.51; §6.2 j (locator checked 2026-09-25)
- Fact checked on
- 2026-09-25
Epidote — care (wear): cleaves or fractures easily or is brittle (e.g. rubbed facet edges); wear with care.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code b
- Treatment state
- any treatment state
Source & check 2026-09-25
- Source
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) (CIBJO): §8 Annex C, Epidote, p.51; §6.2 b (locator checked 2026-09-25)
- Fact checked on
- 2026-09-25
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
Common care questions and matching entries
Care of Epidote: according to the care entries registered for Epidote in the CIBJO Official Gemstone Book (2022), Epidote must not be cleaned ultrasonically, whatever the treatment state, and Epidote fractures easily and should be worn with care, whatever the treatment state.
This table scrolls sideways on narrow screens.
| Question | Matching entries |
|---|---|
| Can it go in an ultrasonic or steam cleaner? | care (cleaning) |
| Wearing limits (knocks, settings) | cleaves or fractures easily or is brittle (e.g. rubbed facet edges); wear with care |
Durability and wearing
Toughness
Brittle
VerifyNames, standards, technical facts, clauses and sources
Names
Chinese standard nameThe Chinese formal name of Epidote is based on GB/T 16552—2017 Table A.1; the mineralogical name is Epidote, and the GSJ (Japan) formal name is written in kanji. Names in four languagesThe four-language names are the Simplified and Traditional Chinese names, English Epidote and the Japanese names. Recommended listing nameThe suggested listing name is Epidote. Institution usageFor authority wording, the CIBJO Gemmological Laboratories Book 2024 records Epidote; the FTC text on file has been checked and has no wording for Epidote; GIA and Gem-A are unchecked. The English name shown for bodies without a recorded wording is only the Epidote entry's own English name and does not represent their position.
- GSJ (Japan) formal name
- 緑簾石
- Chinese formal name
- 绿帘石 (GB/T 16552—2017 Table A.1)
- Mineralogical name
- Epidote
Four-language names
- 简体中文
- 绿帘石
- 繁體中文
- 綠簾石
- English
- Epidote
- 日本語
- エピドート／緑簾石
See also: Misleading and prohibited trade names · Supplementary name index
Classification
- Origin
- Natural materials
- Material domain
- Natural inorganic gem materials
- Browsing family
- Other silicate minerals
- Identity tier
- Mineral species
- Mineral chemical class
- Silicates
- Construction or treatment status
- Natural identity; treatment status unknown
What it is and how it's identified
The chemical composition of Epidote is Ca2(Al,Fe)3(Si2O7)(SiO4)O(OH), and the phase is epidote; crystalline, monoclinic, with a habit of prismatic crystals or prismatic aggregates, the crystal faces often showing longitudinal striations. Mohs hardness 6–7, one direction of perfect cleavage. Density 3.25–3.5 g/cm³, derived from the clause value 3.40 and its permitted tolerance of +0.10/−0.15; refractive index 1.694–1.78, derived from the clause value 1.729–1.768 and its permitted tolerance of +0.012/−0.035; birefringence 0.019–0.045. Optical character anisotropic, biaxial, negative; transparency transparent to translucent. Untreated Epidote shows strong trichroism in green, brown and yellow, usually no luminescence, and under magnification gas-liquid inclusions, mineral inclusions, growth striations and visible doubling; its lustre is vitreous to greasy. On stability, untreated Epidote partly dissolves in hot hydrochloric acid and dissolves rapidly in hydrofluoric acid.
Registered material facts
Each row carries its own source and check date and can be cited on its own; “—” means the cited source gives no value, not “none”.
Definition
Epidote — nomenclature status: IMA status G: grandfathered (described before the IMA existed, and generally regarded as a valid species).
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Epidote — composition (chemistry): Ca2 (Al,Fe) 3 (Si2O7) (SiO4) O (OH)
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.21 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Epidote — composition (phase): epidote
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Structure
Epidote — structure (overall): crystalline
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.21 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Epidote — structure (crystal system): monoclinic
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.21 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Epidote — structure (crystal habit): prisms or prismatic aggregates, faces usually striated lengthwise.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.21 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Durability
Epidote — Mohs hardness: 6–7
GB/T 16553—2017
Reference points on this site: Talc 1–3, Fluorite 4, Apatite 5–5.5, Orthoclase 6–6.5, Topaz 8, Diamond 10 (Source: GB/T 16553—2017); Gypsum 1.5–2, Calcite 3, Quartz 7 (Source: Handbook of Mineralogy); Corundum 9 (Source: GIA Gem Encyclopedia (care guide))
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.21 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Epidote — cleavage: perfect in one direction
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.21 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Epidote — stability: partly dissolves in hot hydrochloric acid; dissolves rapidly in hydrofluoric acid.
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.21 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Physical properties
Epidote — density: 3.25–3.5 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- Qualification
The clause we cite gives 3.40, with a stated tolerance of +0.10 / -0.15. The range shown here is worked out from that.
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.21 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Optical
Epidote — optic character: biaxial, optically negative (anisotropic)
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.21 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Epidote — refractive index: 1.694–1.78
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- Qualification
The clause we cite gives 1.729–1.768, with a stated tolerance of +0.012 / -0.035. The range shown here is worked out from that.
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.21 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Epidote — birefringence: 0.019–0.045
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.21 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Epidote — transparency: transparent to translucent.
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Epidote — pleochroism: strong trichroism: green, brown, yellow.
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.21 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Epidote — fluorescence (overall): generally none
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.21 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Epidote — spectrum (UV-visible): 445 nm strong absorption band; sometimes has 475 nm weak absorption peak.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.21 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Epidote — spectrum (infrared): In the mid-IR, epidote shows its own diagnostic bands.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.21 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Epidote — magnification: gas-liquid inclusions, mineral inclusions, growth striations, visible doubling of facet edges (birefringence).
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.21 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
body colour2 sources compared
Epidote — body colour: Light to very dark green to brown, reddish brown.
CIBJO Gemmological Laboratories Book 2024
- Treatment state
- untreated
- Qualification
In chapter 7 of the CIBJO Gemmological Laboratories Book, the colour descriptions of Jasper, Alexandrite, Mali Garnet and other entries also name green or a greenish colour.
- General note
- colour alone is not identity
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Epidote — body colour: light to dark green, brown, yellow, black, etc.
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- Qualification
In chapter 5 of GB/T 16553—2017, the colour entries of Serpentine, Peridot, Actinolite and other variety clauses also name green or a greenish colour.
- General note
- colour alone is not identity
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.21 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
How the sources relate
- CIBJO Gemmological Laboratories Book 2024 and GB/T 16553—2017
Both list light to dark green and brown. GB/T 16553—2017 also lists yellow and black; the CIBJO Gemmological Laboratories Book also lists reddish brown.
Quality factors
Epidote — quality factor (lustre): vitreous to greasy
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.21 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
This material (RI / SG midpoints): 1.737 / 3.38; Closest values: 1Augite 1.716 / 3.31, 2Vesuvianite / Idocrase 1.711 / 3.38, 3Hydrogrossular 1.7 / 3.35, 4Tanzanite 1.696 / 3.28, 5Taaffeite 1.721 / 3.61
Show the full chart (330 registered materials)
Outside the full chart's range, drawn as triangles at the edge (RI / SG midpoints): Hematite 3.045/5.12, Synthetic Rutile 2.76/4.26, Rutile 2.753/4.23, Synthetic Moissanite 2.67/3.22
Testing and market
There is no synthetic Epidote on the market; the registered source is the CIBJO Official Gemstone Book (Coloured Stone Commission 2022). Which tests CIBJO's laboratory rules require for epidote, and what each method means, are shown in the rules table on the laboratory testing page.
The tests the CIBJO laboratory protocol requires for this material, and what each method means, are in the protocol table on the laboratory testing page: §6.1.32.
How far testing can go
Epidote — synthetic counterpart on the market: No synthetic counterpart of this material is commercially available
CIBJO Gemstone Book 2022
- Treatment state
- any treatment state
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
Clause-level definitions
Epidote is defined directly in CIBJO Gemmological Laboratories Book 2024 under the term Epidote, as the mineral species epidote, IMA status G, noting that the CIBJO wording is quoted in full under Clause-level definitions on this page; the cross-check shows it is defined directly by CIBJO and also appears in the GB/T annex. Epidote also has an IMA Mineral List entry under the term Epidote, with the formula Ca2(Al2Fe3+)(Si2O7)(SiO4)O(OH) and IMA status G, cross-checked against the RRUFF/IMA master mineral list (public domain data).
This table scrolls sideways on narrow screens.
| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Epidote | 7.2.1.84 | Light to very dark green to brown, reddish brown; transparent to translucent | Defined directly by CIBJO; also present in the GB/T annex. |
| Epidote | IMA Mineral List entry | Epidote Ca2(Al2Fe3+)(Si2O7)(SiO4)O(OH) G 1801 | Cross-checked against the RRUFF/IMA master mineral list (public domain data). |
Evidence and sources
Authority basis and clause sources
Sources
- CIBJO – The World Jewellery Confederation. Gemmological Laboratories Book (Blue Book), Gemmological Commission 2024-1.
- CIBJO – The World Jewellery Confederation. The Gemstone Book (Blue Book), 2022.
- SAMR / SAC (China). GB/T 16552—2017 Gems — Nomenclature.
- RRUFF Project, in partnership with the IMA – International Mineralogical Association. IMA Mineral List.
- Geological Survey of Japan, AIST (Japan). Museum mineral specimens, browse by classification.
Further reading
Related entries and topic cluster
Parent entry and related pages on this site. Rows marked “Planned” are suggested new content and have no link yet.
This table scrolls sideways on narrow screens.
| Page | Content | Status |
|---|---|---|
| Browsing family | Other silicate minerals | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Epidote entry are maintained by the LumaLark wiki and matched one by one to the standard clauses or institutional sources they cite: every fact carries its source (with a clause or page locator) and a check date, so it can be traced back to the original; clause-level definitions also carry a cross-check result. The entry exists so that buyers and sellers can check naming, disclosure and material facts item by item.