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Natural inorganic gem materials · Mineral species · Natural identity; treatment status unknown

Dumortierite

Also known asDumortierite quartz (not a recommended name) · Dumortierite-in-quartz (not a recommended name)

A boron-bearing aluminium silicate mineral species; blue Quartz coloured by dumortierite inclusions must be called Dumortierite-in-quartz instead. Also known as Dumortierite-in-quartz, Dumortierite quartz. 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.

Edited by RalphReviewed by JuneLast updated 2026-10-12Who maintains this page

What this page can answer

This page covers

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

Dumortierite is a boron-bearing chain silicate with a formula of about Al7(BO3)(SiO4)3O3. It is found mainly in aluminum-rich rocks that were regionally metamorphosed, both disseminated within them and in veinlets cutting schists, and also in pegmatitic veins. Crystals are typically fibrous or columnar, forming intimate parallel aggregates of needles, or else massive. Its strong pleochroism reflects its composition and crystal structure. Dumortierite is recognized as an independent mineral species and is associated with quartz, cordierite, kyanite, andalusite, sillimanite, muscovite and rutile.

Scope: Covers an overview of the origin and occurrence of dumortierite as a boron-bearing silicate mineral of regional-metamorphic origin; does not address synthetic or imitation materials.

Sources Handbook of Mineralogy

Where it forms

Aluminum-rich rocks that were regionally metamorphosed; disseminated within them and in veinlets cutting schists

Sources Handbook of Mineralogy

Pegmatitic veins; associated with quartz, cordierite, kyanite, andalusite, sillimanite, muscovite, and rutile

Sources Handbook of Mineralogy

How it forms, step by step

  1. Aluminum-rich rocks undergo regional metamorphism, supplying Al, Si, B, and other components.

    Sources Handbook of Mineralogy

  2. Dumortierite crystallizes in these Al-rich metamorphic rocks, disseminated or filling veinlets that cut the schists.

    Sources Handbook of Mineralogy

  3. It may also crystallize in pegmatitic veins, associated with quartz, cordierite, kyanite, and others.

    Sources Handbook of Mineralogy

  4. Crystals are fibrous or columnar, often forming intimate parallel aggregates of needles or massive material.

    Sources Handbook of Mineralogy

Link to appearance

Dumortierite's colour range runs from a bright smalt-blue through greenish blue, violet, red-violet and purple to brown, and its lustre is vitreous to dull. It is strongly pleochroic — deep blue to violet along X, yellow through red-violet to nearly colourless along Y, and along Z colourless or very pale blue — the colour and pleochroism both reflecting its composition and crystal structure.

Sources Handbook of Mineralogy

Timescale

The source states no absolute geological timescale for dumortierite formation.

Sources Handbook of Mineralogy

Supporting findings

Dumortierite is found mainly in aluminum-rich rocks that were regionally metamorphosed, both disseminated within them and in veinlets cutting schists, and also in pegmatitic veins.

Evidence grade B

Scope: Describes the occurrence environment; not an exhaustive list of localities.

Sources Handbook of Mineralogy

Recorded localities

Authoritative sources list the localities below; the list is not exhaustive.

Locality sketch mapLand outlines only; the map does not depict any national or regional boundary. Dots mark approximate positions. Base map: Natural Earth (public domain).

Africa

Europe

North America

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

Dumortierite is strongly pleochroic. Along X it is deep blue to violet; along Y, yellow through red-violet to nearly colourless; along Z, colourless or a very pale blue.

Evidence grade B

Scope: Describes the pleochroic behavior; related to the composition/structure noted in the source.

Sources Handbook of Mineralogy

Where the name comes from

Dumortierite is named for Eugène Dumortier (1802–1873?), French palaeontologist, of Lyons, France.

Evidence grade B

Scope: 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

Dumortierite is a boron-bearing chain silicate with a formula of about Al7(BO3)(SiO4)3O3.

Evidence grade B

Scope: Describes the composition; not an exact composition of a specific specimen.

Sources Handbook of Mineralogy

Dumortierite is named for the French paleontologist E. Dumortier (1802–1873?).

Evidence grade B

Scope: Concerns naming origin, not geological formation.

Sources Handbook of Mineralogy

Dumortierite ranges from bright smalt-blue through greenish blue, violet, red-violet, and brown, with a vitreous to dull luster.

Evidence grade B

Scope: Describes the color and luster range; the source gives no color-cause mechanism.

Sources Handbook of Mineralogy

Limits of this research

  • Research status: Formation, occurrence or other material-specific findings found in authoritative sources
  • The source states no absolute geological timescale for dumortierite formation.
  • The source gives no specific color-cause mechanism for dumortierite.

Methodology

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
Dumortierite

GB/T 16552—2017 5.1.1 b) · CIBJO Gemmological Laboratories Book 2024 §7.2.1.78 “Dumortierite”

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

Dumortierite is also known by several other names, some of which can refer to different materials in other contexts; use "Dumortierite" to avoid ambiguity.

What this means for you

Before buying, check the recommended listing name "Dumortierite" 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

Numbers in curly braces, such as {111}, are crystallographic face symbols (Miller indices): each marks a set of crystal faces or cleavage planes. They are reproduced as written in the cited source.

Mohs hardness

7–8.5

Cleavage

Distinct on {100}, poor on {110}; parting on {001}

Sources Handbook of Mineralogy

Daily wear

Dumortierite ranks 7–8.5 on the Mohs scale and is a hard material, fairly durable for daily wear, but it has distinct cleavage on {100} and a parting on {001}, so it can split on a directed blow; still avoid hard knocks and scratching.

Care

Clean with warm soapy water and a soft brush; ultrasonic and steam cleaning are usually safe for unfractured material, but as a precaution use only warm soapy water on fractured stones. Avoid chemicals that may attack the material.

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 the material's general properties and does not constitute a durability or safety guarantee for any specific finished product; the durability of treated (filled, dyed, coated) or composite pieces must be assessed separately.

VerifyNames, standards, technical facts, clauses and sources

Names

Besides Dumortierite, the name register records "Dumortierite quartz" and "Dumortierite-in-quartz", for which no restriction on use as a name is recorded (CIBJO Gemmological Laboratories Book 2024 §7.2.1.79 “Dumortierite quartz”).

Standard and listing namesDumortierite is a mineral or material name. GB/T 16552—2017 Annex A does not list Dumortierite, but the standard allows mineral, rock and material-science names not included in Annex A to be used directly, so Dumortierite can be used directly as a name; the suggested listing name is Dumortierite. Names in four languagesNames are registered in four languages: Simplified Chinese, Traditional Chinese, English (Dumortierite) and Japanese, and the GSJ (Japan) has its own formal Japanese name. Institution usageOn authority wording, CIBJO records Dumortierite, the FTC text on file has no wording for Dumortierite (checked), and the wording of GIA and Gem-A is unchecked; bodies without a recorded wording show the entry's own English name, which does not represent their position. Sub-names and unacceptable namesDumortierite quartz and Dumortierite-in-quartz are market names; neither is aligned to Dumortierite and both are marked as not recommended, and Dumortierite-in-quartz refers only to quartz material containing dumortierite and is not a synonym for Dumortierite.

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.

NameTypeMatchingUse as a nameBasis
no restriction recorded (2)
Dumortierite quartzEnglishmarket namenever matched to this entryno restriction recordedCIBJO Gemmological Laboratories Book 2024 §7.2.1.79 “Dumortierite quartz”; Note: This name refers to quartz with visible dumortierite inclusions: the material is quartz, not dumortierite, so it is not matched to this entry.
Dumortierite-in-quartzEnglishmarket namenever matched to this entryno restriction recordededitorial ruling (no clause cited); Note: This name refers only to quartz that contains dumortierite. It is not another name for dumortierite, so it is not matched to this entry.

How each authority words this name: see Names › Authority wording.

Authority wording

GIA, FTC, CIBJO, Gem-A
Dumortierite (on record for CIBJO (CIBJO Gemmological Laboratories Book 2024 §7.2.1.78); no wording for this name in the FTC text on file; GIA, Gem-A unchecked — bodies without a recorded wording show the entry's own English name)
GSJ (Japan) formal name
デュモルチ石
Mineral / material name (not in GB/T 16552 Annex A; usable directly)
蓝线石 (GB/T 16552—2017 §5.1.1 b))
Mineralogical name
Dumortierite (Al7BO3(SiO4)3O3)
Trade names and synonyms
Dumortierite-in-quartz (market name; not a recommended name) · Dumortierite quartz (market name; not a recommended name)

Four-language names

简体中文
蓝线石
繁體中文
藍線石
English
Dumortierite
日本語
デュモルチェライト／デュモルチ石

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 registered material facts for Dumortierite are as follows. Its nomenclature status is IMA status Rd, redefined: a mineral already known that was given a new definition in the IMA era. Its composition is the phase dumortierite, and its transparency is translucent to opaque. In the untreated state its body colour is dark blue, violet blue, blue, colourless, pink or red. This site notes that in chapter 7 of the CIBJO Gemmological Laboratories Book the colour descriptions of entries such as taaffeite, benitoite and sugilite also mention blue or bluish colours.

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

Dumortierite — nomenclature status: IMA status Rd: redefined (a mineral already known, given a new definition in the IMA era).

CIBJO Gemmological Laboratories Book 2024

Source & check 2026-09-22
Source
Fact checked on
2026-09-22

Dumortierite — composition (phase): dumortierite

CIBJO Gemmological Laboratories Book 2024

Source & check 2026-09-22
Source
Fact checked on
2026-09-22

Optical

Dumortierite — transparency: translucent, opaque.

CIBJO Gemmological Laboratories Book 2024

Source & check 2026-09-22
Source
Fact checked on
2026-09-22

Dumortierite — body colour: Dark blue, violet blue, colourless, pink, red.

CIBJO Gemmological Laboratories Book 2024

Treatment state
untreated
Qualification

In chapter 7 of the CIBJO Gemmological Laboratories Book, the colour descriptions of Taaffeite, Benitoite, Sugilite and other entries also name blue or a bluish colour.

General note
colour alone is not identity
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.

Testing and market

The tests the CIBJO laboratory protocol requires for Dumortierite, and what each method covers, are given in the protocol table on the laboratory testing page. On how far testing can go, the Dumortierite row in Annex C of the CIBJO Official Gemstone Book (2022) concludes that there is no synthetic Dumortierite on the market.

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: §6.1.28.

How far testing can go

Dumortierite — 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

In the clause-level definitions, the CIBJO Gemmological Laboratories Book 2024 gives a direct definition under the term Dumortierite, listing the colours as dark blue, violet-blue, colourless, pink and red, and the transparency as translucent or opaque; the cross-check result is defined directly by CIBJO, with no English term of the same name found directly in the GB/T annex of this edition. A further basis is the IMA mineral list entry, recorded as Dumortierite AlAl6BSi3O18 Rd 2013 s.p., cross-checked against the RRUFF/IMA mineral list master table, using public-domain data.

This table scrolls sideways on narrow screens.

TermClauseDefinitionCross-check
Dumortierite7.2.1.78Dark blue, violet blue, colourless, pink, red, translucent, opaqueDefined directly by CIBJO; no identically named English entry was found in this edition of the GB/T annex.
DumortieriteIMA Mineral List entryDumortierite AlAl6BSi3O18 Rd 2013 s.p.Cross-checked against the RRUFF/IMA master mineral list (public domain data).

Evidence and sources

Authority basis and clause sources

GB/T 16552—2017
Not listed the name does not occur anywhere in the text; scope: Chapter 1 “Scope” · Source
GB/T 16552—2017
Naming rule 5.1.1 b) · Source
CIBJO Gemmological Laboratories Book 2024
Listed §7.2.1.78 “Dumortierite” · Source
IMA Mineral List 2026-07
Listed “Dumortierite” · Source

Sources

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.

PageContentStatus
Browsing familyOther silicate mineralsLive
Related articlesTo be added (placeholder)Planned

Who maintains this page

The material facts in the Dumortierite 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.

Facts editor
Ralph
Reviewer
June
How facts are checked
Each fact is matched to the clause it cites; facts checked on 2026-09-22
Last revised
2026-10-12
Purpose
Lets buyers and sellers check naming, disclosure and material facts clause by clause.

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