On this page
UnderstandWhat it is, what people ask, how far this page goes
Natural inorganic gem materials · Mineral / gemstone variety · Natural identity; treatment status unknown
Hackmanite
Also known asTenebrescent sodalite
A variety of Sodalite that changes colour reversibly under ultraviolet light; this photochromism is an inherent feature, not a treatment. 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 Hackmanite 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 HackmaniteHow far lab testing can go
- Caring for and wearing HackmaniteCleaning, heat, chemicals and light, as the cited sources give them; durability indicators and wearing advice
- Hardness, density and refractive index of HackmaniteEach value with its source and check date
- Hackmanite in English, Chinese and Japanese; national standard namesNames in four languages, the GB/T standard name and the suggested listing name; and: Has any of GIA, FTC, CIBJO or Gem-A put a name for it on record here?
- Name origin and history of HackmaniteWhere the name comes from
- Listing and disclosing HackmaniteThe listing name to use; what must be disclosed before sale
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
Blue sodalite is a colour variety of the mineral sodalite (Na8Al6Si6O24Cl2, a member of the sodalite group) named for its blue hue; the variety that shows reversible tenebrescence/photochromism is termed hackmanite, whose general formula is Na8Al6Si6O24(Cl,S)2. Sodalite is found in nepheline syenite, phonolite and allied rocks, in calcareous rocks that have undergone metasomatism, and in cavities inside ejected volcanic blocks. In recent years, notable quantities of gem-quality sodalite/hackmanite - some of it unusually transparent - have come from Myanmar's Mogok region and Afghanistan's Badakhshan Province; EDXRF analysis detected traces of sulfur in every sample. Hackmanite is one of a group of nature-based smart materials: it changes colour when exposed to UV or X-rays and can revert.
Scope: Applies to an overview of the naming boundary, composition, occurrence and tenebrescence mechanism of hackmanite as a variety of sodalite; the specific variety assignment and locality require identification.
Sources Gems & Gemology (Hackmanite) · Handbook of Mineralogy · Advanced Optical Materials (2021)
Where it forms
Occurs in nepheline syenite, phonolite and allied rock types, as well as in calcareous rocks that have been metasomatised and in cavities within ejected volcanic blocks.
Sources Gems & Gemology (Hackmanite) · Handbook of Mineralogy
Gem-quality producing localities: Mogok (Myanmar) and Badakhshan (Afghanistan).
Sources Gems & Gemology (Hackmanite) · Handbook of Mineralogy
How it forms, step by step
Sodalite crystallizes in nepheline syenites, phonolites, metasomatized calcareous rocks, or cavities in volcanic blocks.
Sources Gems & Gemology (Hackmanite) · Handbook of Mineralogy
Where sulfur/defect-related centres occur in the structure, sodalite can show reversible photochromism (becoming hackmanite).
Sources Gems & Gemology (Hackmanite) · Handbook of Mineralogy
UV or X-ray exposure colours hackmanite, and it can gradually revert afterwards.
Sources Gems & Gemology (Hackmanite) · Handbook of Mineralogy
Link to appearance
Blue sodalite is blue (sodalite may be colourless, white, yellowish, greenish, light to dark blue or reddish; colourless to gray in thin section); the hackmanite variety deepens or changes colour after UV/X-ray exposure and reverts afterwards.
Sources Gems & Gemology (Hackmanite) · Handbook of Mineralogy · Advanced Optical Materials (2021)
Timescale
The sources give no absolute timescale for sodalite formation or for the photochromic process.
Sources Gems & Gemology (Hackmanite) · Handbook of Mineralogy · Advanced Optical Materials (2021)
Related base materials
- Sodalite (Na8Al6Si6O24Cl2): Hackmanite is a variety of sodalite; material showing reversible photochromism is called hackmanite
Supporting findings
Sodalite is found in nepheline syenite, phonolite and allied rocks, in calcareous rocks that have undergone metasomatism, and in cavities inside ejected volcanic blocks.
Evidence grade BScope: Occurrence/genesis of the species.
Sources Handbook of Mineralogy
Gem-quality sodalite/hackmanite, some of it unusually transparent, has come in recent years from Myanmar's Mogok region and from Afghanistan's Badakhshan Province; EDXRF work detected traces of sulfur in every sample.
Evidence grade AScope: Localities and detection for the samples studied.
Sources Gems & Gemology (Hackmanite)
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
Asia
- Mogok area, Myanmar
Sources Gems & Gemology (Hackmanite)
- Badakhshan Province, Afghanistan
Sources Gems & Gemology (Hackmanite)
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
Hackmanite shows reversible photochromism/tenebrescence: it changes colour upon UV or X-ray exposure and can revert, and is regarded as a family of nature-based smart materials.
Evidence grade AScope: An optical (photochromic) mechanism statement.
Sources Advanced Optical Materials (2021)
Sodalite may be colourless, white, yellowish, greenish, light to dark blue, or reddish (colourless to gray in thin section); the tenebrescence of many hackmanite stones is strong enough for classification as hackmanite.
Evidence grade AScope: Colour description and the basis for variety classification.
Sources Handbook of Mineralogy · Gems & Gemology (Hackmanite)
Where the name comes from
The origin of the trade name "blue sodalite" is not given in the cited sources. The etymology below belongs to the parent mineral sodalite, whose name is in allusion to its sodium content. This etymology belongs to the parent mineral, not to the commercial variety name "blue sodalite" itself.
Evidence grade BScope: The etymology explains only the origin of the name; it does not establish the material's composition, locality, naturalness, or treatment.
Sources Handbook of Mineralogy
Other research findings
Blue sodalite is a variety of sodalite, not an independent mineral species; the variety showing reversible tenebrescence/photochromism is called hackmanite.
Evidence grade AScope: Naming and variety classification.
Sources Gems & Gemology (Hackmanite) · Advanced Optical Materials (2021)
Sodalite has the formula Na8Al6Si6O24Cl2 and belongs to the sodalite group; the hackmanite variety has the general formula Na8Al6Si6O24(Cl,S)2 (sulfur-bearing).
Evidence grade AScope: Describes composition and group membership.
Sources Handbook of Mineralogy · Advanced Optical Materials (2021)
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- The specific colouring mechanism of sodalite (which element/colour centre causes blue) is not given in the sources consulted, so this record makes no blue-colour-cause assertion.
- No absolute timescale for sodalite formation or for the photochromic process is given by the sources.
- The database marks this name as "clear" (a sodalite variety); this record substantiates it from GIA and mineralogical sources.
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
- Hackmanite
GB/T 16552—2017 5.1.1 c)
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
Hackmanite is Sodalite variety exhibiting tenebrescence (reversible colour change on UV exposure); use "Hackmanite" for listings, and disclose any known treatments.
What this means for you
Before buying, check the recommended listing name "Hackmanite" 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
Care
Hackmanite — care (heat): the same paper states that heating hackmanite above 500 °C permanently ends its UV-driven colour change, leaving it bleached.
Gems & Gemology 2009 (Kondo et al.)
- Treatment state
- any treatment state
Source & check 2026-10-06
- Source
- D. Kondo & D. Beaton, “Hackmanite/Sodalite from Myanmar and Afghanistan”, Gems & Gemology 45(1): 38–43 (2009): p.38, body text (locator checked 2026-10-06)
- Fact checked on
- 2026-10-06
Hackmanite — care (light): a 2009 G&G study reports that in most hackmanite the UV-induced colour bleaches when the stone is exposed to daylight or white artificial light.
Gems & Gemology 2009 (Kondo et al.)
- Treatment state
- any treatment state
Source & check 2026-10-06
- Source
- D. Kondo & D. Beaton, “Hackmanite/Sodalite from Myanmar and Afghanistan”, Gems & Gemology 45(1): 38–43 (2009): p.38, body text (locator checked 2026-10-06)
- Fact checked on
- 2026-10-06
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
Each question links to the matching entries on this page; whether they answer it fully, go by the entry wording.
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Durability and wearing
Toughness
Brittle
How lab reports word it
A general LMHC wording rule also covers Hackmanite (Information Sheet #16): see the LMHC rule “Colour stability testing”.
VerifyNames, standards, technical facts, clauses and sources
Names
Besides Hackmanite, the name register records "Tenebrescent sodalite", for which no restriction on use as a name is recorded.
Standard and listing namesHackmanite is not listed under its own name in GB/T 16552—2017 Table A.2; the corresponding national-standard name is sodalite. The suggested listing name is blue sodalite (Hackmanite). Names in four languagesNames are given in Simplified Chinese, Traditional Chinese, English (Hackmanite) and Japanese. On the GSJ (Japan) formal name, the entry has its own Japanese name for Hackmanite, and the wording used by GSJ (Japan) for this name has not yet been verified. Trade and mineralogical namesThe mineralogical name describes the variety of sodalite that shows photochromism (a reversible colour change under ultraviolet light); the trade name/synonym is Tenebrescent sodalite, which is also registered as an English synonym. Institution usageAmong GIA, FTC, CIBJO and Gem-A, the FTC and CIBJO texts contain no wording for this name (checked), while GIA and Gem-A are unchecked; bodies without a recorded wording show the English name Hackmanite, which does not represent their position.
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 (1) | ||||
| Tenebrescent sodaliteEnglish | synonym | matched automatically | no restriction recorded | editorial ruling (no clause cited) |
How each authority words this name: see Names › Authority wording.
- GSJ (Japan) formal name
- ハックマナイト (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)
- 方钠石 (GB/T 16552—2017 Table A.2)
- Mineralogical name
- Sodalite variety exhibiting tenebrescence (reversible colour change on UV exposure)
- Trade names and synonyms
- Tenebrescent sodalite (synonym)
Four-language names
- 简体中文
- 蓝方钠石
- 繁體中文
- 藍方鈉石
- English
- Hackmanite
- 日本語
- ハックマナイト
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
In the cited clause, the material facts for Hackmanite are registered for sodalite (the whole class); they are not measurements of Hackmanite itself. For sodalite (the whole class), Hackmanite is crystalline or a crystalline aggregate, cubic, with a rhombic dodecahedral habit, often as granular or massive aggregates; Mohs hardness 5–6, cleavage usually not seen in aggregates, and untreated, it is etched by hydrochloric acid. Density 2.15–2.4 g/cm³ is derived from the clause value of 2.25 with tolerances of +0.15 and −0.10; optic character isotropic, often as an aggregate; refractive index 1.479–1.487, derived from the clause value of 1.483 with a tolerance of ±0.004; birefringence none; untreated, pleochroism none; among optical effects, colour change is visible; untreated, lustre vitreous to greasy. Whole-class features such as chemical composition are registered for sodalite (the whole class); see the Sodalite entry.
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 sodalite (the whole class), so they are not repeated on the Hackmanite page; see the material facts on the Sodalite entry.
Items below that name the class they cover give the cited clause’s value for that whole class, not a measurement of Hackmanite (how to read class-level values).
Structure
Hackmanite — structure (overall): crystalline, or else a crystalline aggregate
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- sodalite (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.27 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Hackmanite — structure (crystal system): cubic system
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- sodalite (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.27 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Hackmanite — structure (crystal habit): rhombic dodecahedra; mostly granular or massive aggregates.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- sodalite (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.27 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Durability
Hackmanite — Mohs hardness: 5–6
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
- sodalite (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.27 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Hackmanite — cleavage: generally not seen on an aggregate
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- sodalite (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.27 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Hackmanite — stability: is corroded by hydrochloric acid
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- sodalite (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.27 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Physical properties
Hackmanite — density: 2.15–2.4 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- sodalite (the whole class)
- Qualification
The clause we cite gives 2.25, with a stated tolerance of +0.15 / -0.10. The range shown here is worked out from that.
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.27 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Optical
Hackmanite — optic character: isotropic; usually found as an aggregate
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- sodalite (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.27 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Hackmanite — refractive index: 1.479–1.487
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- sodalite (the whole class)
- Qualification
The clause we cite gives 1.483, with a stated tolerance of ±0.004. The range shown here is worked out from that.
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.27 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Hackmanite — birefringence: none
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- sodalite (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.27 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Hackmanite — pleochroism: none
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- sodalite (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.27 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Hackmanite — optical effect (colour change): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- sodalite (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.27 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
- CIBJO definitions
- colour change
Quality factors
Hackmanite — quality factor (lustre): vitreous to greasy
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- sodalite (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.27 (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): 1.483 / 2.27; Closest values: 1Tektite / Moldavite 1.495 / 2.36, 2Obsidian 1.495 / 2.4, 3Chrysocolla 1.516 / 2.2, 4Haüyne 1.5 / 2.46, 5Synthetic Opal 1.45 / 2.08
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
In the CIBJO laboratory protocol, Hackmanite is covered under Sodalite: for the identification of Hackmanite see the identification part of the Sodalite entry, and the list of required tests is on the laboratory testing page. The instrumental testing lead registered under GB/T 16553—2017 Gems — Testing is that untreated Hackmanite appears reddish brown through the Chelsea colour filter; in the original this Chelsea filter lead is written for sodalite as a whole class and is not a measurement of Hackmanite alone.
The CIBJO laboratory protocol covers Hackmanite under “Sodalite” (§6.1.76): see identification on the Sodalite entry; the required tests are listed on the CIBJO laboratory protocol table for Sodalite.
How far testing can go
Hackmanite — how far testing can go (instrumental testing): appears reddish brown under the Chelsea colour filter
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- sodalite (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.27 (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.
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.
- GIA – Gemological Institute of America (United States). Gem Encyclopedia.
- Gem-A – The Gemmological Association of Great Britain (United Kingdom).
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.
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| 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 Hackmanite 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. The entry exists so that buyers and sellers can check naming, disclosure and material facts item by item.