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UnderstandWhat it is, what people ask, how far this page goes
Natural inorganic gem materials · Mineral / gemstone variety · Natural identity; treatment status unknown
Thulite
Also known asPink zoisite
A pink, manganese-colored variety of zoisite. Its mineral species is still Zoisite, and it is not a separate mineral species itself. Also known as Pink zoisite. 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 Thulite 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 ThuliteHow far lab testing can go and whether a synthetic exists
- Caring for and wearing ThuliteDurability indicators and wearing advice
- Hardness, density and refractive index of ThuliteEach value with its source and check date
- Thulite 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 ThuliteWhere the name comes from
- Listing and disclosing ThuliteThe listing name to use; what must be disclosed before sale
- Standard clauses that define ThuliteWhich 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
Thulite is the pink, manganese-bearing gem variety of zoisite. Zoisite, whose approximate formula is Ca2Al3(SiO4)(Si2O7)O(OH), is a member of the epidote group and is dimorphous with clinozoisite. Its usual hosts are crystalline schists of medium metamorphic grade that were regionally metamorphosed, developed from calcium-rich igneous, sedimentary or metamorphic precursors, and also rocks of eclogite and blueschist facies. Within these settings thulite appears as the pink manganese-coloured form of zoisite, matching its pleochroic tints from pink through to red-violet.
Scope: Applies to an overview of the formation and occurrence of thulite as the pink manganese-bearing variety of zoisite; its parent mineral is zoisite (epidote group).
Sources Handbook of Mineralogy
Where it forms
Crystalline schists of medium metamorphic grade, regionally metamorphosed, developed from igneous, sedimentary or metamorphic precursors that are comparatively calcium-rich.
Sources Handbook of Mineralogy
Rocks of eclogite and blueschist facies.
Sources Handbook of Mineralogy
How it forms, step by step
Protoliths relatively high in calcium (igneous, sedimentary or metamorphic) enter a regional metamorphic setting.
Sources Handbook of Mineralogy
Zoisite crystallizes under medium-grade metamorphic conditions, associated with garnet, albite, biotite, hornblende, quartz and calcite.
Sources Handbook of Mineralogy
Under particular manganese-bearing conditions the zoisite is pink, forming the thulite variety.
Sources Handbook of Mineralogy
It may also coexist in eclogite and blueschist-facies metamorphic assemblages.
Sources Handbook of Mineralogy
Link to appearance
Thulite ranges from pink to red-violet. Its pleochroism is diagnostic: the X direction looks pale pink to red-violet, Y is nearly colourless or bright pink to deep blue, and Z spans pale yellow through yellow-green.
Sources Handbook of Mineralogy
Timescale
No dating figure for thulite/zoisite metamorphism was available, so no timescale is stated.
Sources Handbook of Mineralogy
Supporting findings
Zoisite—and therefore thulite—typically occurs in crystalline schists of regionally metamorphosed, medium-grade terranes derived from calcium-rich igneous, sedimentary or metamorphic rocks, and in rocks of eclogite and blueschist facies.
Evidence grade BScope: Describes zoisite's general occurrence, applicable to thulite as its variety; not thulite-specific localities.
Sources Handbook of Mineralogy
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
Europe
- Kleppan, Sauland, Hjartdal, Telemark, NorwayLocality of original description; G&G notes it is Norway's national gemstone and was discovered there
Sources Mindat: Zoisite · Gems & Gemology Spring 2020
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
Zoisite (including thulite) shows colours including pink, blue, purple, white and grey; the pink is related to manganese.
Evidence grade BScope: Applies to the colour range of zoisite; this record links pink to manganese without quantitative data.
Sources Handbook of Mineralogy
Where the name comes from
Thulite is a pink, manganese-bearing variety of zoisite; the etymology cited belongs to its species zoisite, which commemorates Siegmund Zois, Baron von Edelstein (1747–1819), who supplied the first specimens.
Evidence grade BScope: The etymology explains the origin of a name only; it does not attest composition, locality, naturalness or treatment, and here belongs to the parent mineral rather than to the trade name itself.
Sources Handbook of Mineralogy
Other research findings
Thulite is a pink, manganese-bearing gem variety of zoisite; zoisite belongs to the epidote group and is dimorphous with clinozoisite.
Evidence grade BScope: Defines thulite as a variety of its parent zoisite; does not claim it is a separate mineral species.
Sources Handbook of Mineralogy
Zoisite has the composition approximately Ca2Al3(SiO4)(Si2O7)O(OH).
Evidence grade BScope: Applies to the composition of zoisite (including thulite); trace Mn causes the colour.
Sources Handbook of Mineralogy
Zoisite has a perfect cleavage and hardness 6-7; its associated minerals indicate a metamorphic origin.
Evidence grade BScope: Supplementary physical properties and paragenesis as a genetic indicator; not locality determination.
Sources Handbook of Mineralogy
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- Based on the Handbook of Mineralogy 'Zoisite' data sheet (level B); no thulite-specific source has been found, and the 'Mn-bearing pink' definition lacks a quantitative Mn figure here.
- One downloaded source file turned out to be an error page and was not used as evidence.
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
- Thulite
IMA Mineral List 2026-07 “Zoisite” · CIBJO Gemmological Laboratories Book 2024 §7.2.1.239 “Thulite”
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
Thulite is also known by several other names, some of which can refer to different materials in other contexts; use "Thulite" to avoid ambiguity.
Evidence
- CIBJO · 7.2.1.239
What this means for you
Before buying, check the recommended listing name "Thulite" 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
No institutional care guidance is registered for this material yet; below are its durability indicators and general guidance.
Durability and wearing
Toughness
Brittle
Daily wear
Thulite (pink zoisite) is Mohs 6–7 and fairly durable for daily wear, but brittle with one perfect cleavage, so it is vulnerable to impact fracture and scratching.
Care
Clean with warm water, mild soap and a soft cloth; avoid ultrasonic/steam cleaners if fractured; avoid impact and chemicals.
General guidance: LumaLark's general guidance inferred from the material's properties (hardness, toughness, cleavage); not text from the cited source, and not a guarantee for any specific piece.
Scope: This field describes general material properties and does not constitute a durability or safety warranty for any specific finished product; the durability of treated (filling/dyeing/coating) or assembled pieces must be assessed separately.
VerifyNames, standards, technical facts, clauses and sources
Names
Besides Thulite, the name register records "Pink zoisite", for which no restriction on use as a name is recorded; 3 further names in non-Latin scripts are listed in the name register below (2 with no restriction recorded on use as a name, 1 that may appear only as an annotation, never as the product name).
Standard and listing namesFor the GB/T naming counterpart of Thulite, the name itself is not listed in the standard, and the corresponding name is Zoisite (GB/T 16552—2017 Table A.1). The suggested listing name is Thulite. Institution usageThe CIBJO Gemmological Laboratories Book 2024 records Thulite; the FTC text on file has no wording for this name (checked); GIA and Gem-A are unchecked. Bodies without a recorded wording show the English name of Thulite, which does not represent their position. Japanese namesFor the GSJ (Japan) formal name, the entry's own Japanese names are shown, and GSJ's wording for them is not yet verified by this site. Sub-names and unacceptable namesTrade names or synonyms include Chinese names meaning rose zoisite, manganese zoisite and red zoisite, and Pink zoisite; of these, red zoisite is a market search term, not recommended, which may only be added as a note and must not be the main product name, as red is not a controlled colour-variety name for zoisite. Names in four languagesThe Simplified Chinese, Traditional Chinese, English and Japanese names are given, the English being Thulite. Trade and mineralogical namesThe mineralogical name is a pink, manganese-coloured variety of zoisite.
Name register
Every name recorded for this entry, with how it is classified, whether it may be matched to this entry automatically, whether it may be used as a product name, and the clause it rests on.
This table scrolls sideways on narrow screens.
| Name | Type | Matching | Use as a name | Basis |
|---|---|---|---|---|
| no restriction recorded (3) | ||||
| Pink zoisiteEnglish | market name | matched automatically | no restriction recorded | editorial ruling (no clause cited) |
| 玫瑰黝帘石Simplified Chinese | market name | matched automatically | no restriction recorded | editorial ruling (no clause cited) |
| 锰黝帘石Simplified Chinese | market name | matched automatically | no restriction recorded | editorial ruling (no clause cited) |
| annotation only, never as the product name (1) | ||||
| 红黝帘石Simplified Chinese | market name | matched automatically | annotation only, never as the product name | editorial ruling (no clause cited); Note: Formerly a separate entry, merged here on 2026-09-13: it duplicated thulite, and “red” is not a controlled colour-variety name for zoisite (the controlled split is by colouring element: manganese gives pink, chromium gives green, and blue-violet material is called tanzanite). Kept only as a market search term. |
How each authority words this name: see Names › Authority wording.
- GSJ (Japan) formal name
- ツーライト／桃簾石 (not yet checked for this body — the entry's own Japanese name is shown)
- GB/T naming counterpart (this name is not in the standard)
- 黝帘石 (GB/T 16552—2017 Table A.1)
- Mineralogical name
- Pink manganese-bearing zoisite variety
- Trade names and synonyms
- Pink zoisite (market name)
Four-language names
- 简体中文
- 桃帘石
- 繁體中文
- 桃簾石
- English
- Thulite
- 日本語
- ツーライト／桃簾石
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 / gemstone variety
- Mineral chemical class
- Silicates
- Construction or treatment status
- Natural identity; treatment status unknown
What it is and how it's identified
The composition (phase) of Thulite is zoisite. Registered for zoisite as a whole mineral species: structure crystalline, orthorhombic, with a prismatic or tabular-prismatic habit; Mohs hardness 6–7, with one direction of perfect cleavage; density 3.1–3.45 g/cm³, where the cited clause gives 3.35 with a permitted tolerance of +0.10/−0.25 and the range is derived from this; optical character anisotropic, biaxial, positive; refractive index 1.686–1.705, from the clause value 1.691–1.700 with a permitted tolerance of ±0.005, from which the range is derived; birefringence 0.008–0.013; quality factor (lustre) vitreous, treatment status untreated. The transparency of Thulite is translucent to opaque, and the body colour is pink, often mottled with grey or white, with the body colour entry having treatment status untreated.
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”.
Chemical composition, luminescence, UV-visible spectrum, infrared spectrum, magnification: these whole-class features are given in the cited clause for zoisite (the whole mineral species), so they are not repeated on the Thulite page; see the material facts on the Zoisite entry.
Items below that name the class they cover give the cited clause’s value for that whole class, not a measurement of Thulite (how to read class-level values).
Definition
Thulite — composition (phase): zoisite
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Structure
Thulite — structure (overall): crystalline
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- zoisite (the whole mineral species)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.20 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Thulite — structure (crystal system): orthorhombic
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- zoisite (the whole mineral species)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.20 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Thulite — structure (crystal habit): columnar or platy-columnar
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- zoisite (the whole mineral species)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.20 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Durability
Thulite — 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
- What this covers
- zoisite (the whole mineral species)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.20 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Thulite — cleavage: perfect in one direction
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- zoisite (the whole mineral species)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.20 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Physical properties
Thulite — density: 3.1–3.45 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- zoisite (the whole mineral species)
- Qualification
The clause we cite gives 3.35, with a stated tolerance of +0.10 / -0.25. The range shown here is worked out from that.
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.20 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Optical
Thulite — optic character: biaxial, optically positive (anisotropic)
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- zoisite (the whole mineral species)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.20 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Thulite — refractive index: 1.686–1.705
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- zoisite (the whole mineral species)
- Qualification
The clause we cite gives 1.691–1.700, with a stated tolerance of ±0.005. The range shown here is worked out from that.
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.20 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Thulite — birefringence: 0.008–0.013
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- zoisite (the whole mineral species)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.20 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Thulite — transparency: translucent to opaque.
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Thulite — pleochroism: trichroism, strong. In blue tanzanite the three colours are blue, purple-red and green-yellow; brown stones show green, purple and light blue; yellow-green stones show dark blue, yellow-green and purple.
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- zoisite (the whole mineral species)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.20 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Thulite — optical effect (chatoyancy): seen; rare
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- zoisite (the whole mineral species)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.20 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Thulite — body colour: Pink, translucent to opaque, often mottled with grey or white.
CIBJO Gemmological Laboratories Book 2024
- Treatment state
- untreated
- Qualification
In chapter 7 of the CIBJO Gemmological Laboratories Book, the colour descriptions of Pectolite, Rhodochrosite, Tremolite and other entries also name pink or a pinkish colour.
- General note
- colour alone is not identity
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
- CIBJO definitions
- chatoyancy
Quality factors
Thulite — quality factor (lustre): vitreous
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- zoisite (the whole mineral species)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.20 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
This material (RI / SG midpoints): 1.696 / 3.28; Closest values: 1Axinite 1.683 / 3.31, 2Hydrogrossular 1.7 / 3.35, 3Enstatite 1.712 / 3.31, 4Fei Cui / Jadeite Jade 1.683 / 3.35, 5Kornerupine 1.673 / 3.31
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
Under CIBJO's laboratory rules, Thulite falls under the zoisite entry; identification leads are in the zoisite entry, and the list of required methods is on the laboratory testing page. According to the CIBJO Official Gemstone Book (2022), there is no synthetic thulite on the market.
The CIBJO laboratory protocol covers Thulite under “Zoisite” (§6.1.92): see identification on the Zoisite entry; the required tests are listed on the CIBJO laboratory protocol table for Zoisite.
How far testing can go
Thulite — 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
Thulite is defined directly in CIBJO Gemmological Laboratories Book 2024 under the term Thulite; the entry states that its mineral species is zoisite and that Thulite is the mineral/gem variety thulite, with the CIBJO wording quoted in full under Clause-level definitions on this page. The cross-check concludes that it is defined directly by CIBJO, and no identically named English entry was found in this edition of the GB/T annex.
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| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Thulite | 7.2.1.239 | Pink, translucent to opaque, often mottled with grey or white, massive variety of zoisite | Defined directly by CIBJO; no identically named English entry was found in this edition of the GB/T annex. |
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 Thulite 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.