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
Howlite
A mineral species listed in GB/T 16552-2017 Appendix A.2; the market often dyes Howlite to imitate Turquoise, and dyeing must be disclosed. 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.
Questions people ask about Howlite
Every sentence below is followed by the registered fact it rests on; answers add no new facts and promise no outcome.
Q1Is coloured howlite dyed?
Howlite's natural colour is white, often with a dark grey and black spiderweb matrix.CIBJO Gemmological Laboratories Book 2024CIBJO's Gemstone Book records dyeing of howlite in the trade as almost always applied.CIBJO Gemstone Book 2022The dyeing is recorded as unstable.CIBJO Gemstone Book 2022
Q2How can you tell whether howlite has been dyed or imitated?
In dyed howlite the colour is uneven under magnification and gathers in fissures, between grains or in surface hollows, and wiping with acetone or absolute ethanol can lift it.GB/T 16553—2017No synthetic howlite is commercially available.CIBJO Gemstone Book 2022Dyed howlite is a common turquoise imitation, and infrared spectra clearly separate turquoise from it.G&G Winter 2024 · CIBJO Gemstone Book 2022Whether one particular bead is natural, treated or synthetic — only a laboratory report can settle that.What this page can answer
Q3What kind of mineral is howlite?
Howlite is a calcium borosilicate mineral with the ideal formula Ca2B5SiO9(OH)5.Handbook of MineralogyIt is white with a subvitreous lustre and a hardness of 3.5; massive material looks chalky to porcelain-like.Handbook of MineralogyIt is named after Henry How, the Canadian chemist, geologist and mineralogist who first described it in Nova Scotia.Handbook of Mineralogy
Q4Does howlite scratch easily?
Yes: its hardness is recorded as 3.5 on the Mohs scale.Handbook of MineralogyCIBJO's care guidance for dyed howlite notes that low hardness makes it prone to scratching, so it should be worn with care.CIBJO Gemstone Book 2022
Q5How should howlite be cleaned, and can it get wet?
Dyed howlite should not go in an ultrasonic cleaner.CIBJO Gemstone Book 2022Dyed howlite is porous and should be kept away from coloured fluids, all solvents including dish-washing liquid, other chemicals and heat, because the dye is not permanent.CIBJO Gemstone Book 2022
Q6Where does howlite come from?
Howlite occurs in borate deposits, most commonly as nodules.Handbook of MineralogyIt is found with other borate minerals such as colemanite, ulexite and bakerite.Handbook of Mineralogy
Q7Does howlite have healing or calming powers?
There is no scientific evidence that howlite has healing powers: the UK advertising regulators ASA and CAP state that they have not seen evidence that crystal therapy can treat medical conditions.ASA/CAP guidance (UK)
Sources cited in these answers ASA/CAP guidance (UK)
What this page can answer
This page covers
- How Howlite forms and what gives its colourFormation setting, process and timescale, each finding graded and sourced
- How to identify HowliteIdentification points from the research literature; how far lab testing can go and whether a synthetic exists
- Treatments and enhancements of Howlite1 registered treatments: status, stability, how common they are and identification leads
- Caring for and wearing HowliteCleaning, heat, chemicals and light, as the cited sources give them; durability indicators and wearing advice
- Hardness, density and refractive index of HowliteEach value with its source and check date
- Howlite 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 HowliteWhere the name comes from
- Listing and disclosing HowliteThe listing name to use; what must be disclosed before sale
- Standard clauses that define HowliteWhich 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
Howlite is a monoclinic borosilicate species with ideal composition Ca2B5SiO9(OH)5. It occurs in borate deposits, most commonly as nodules; when massive it is chalky to porcelaneous, and it is associated with borate minerals such as colemanite and ulexite.
Scope: Applies to the genesis and occurrence of natural howlite as a borosilicate mineral species; does not cover synthetic, dyed or imitation materials.
Sources Handbook of Mineralogy
Where it forms
In borate deposits, most commonly as nodules
Sources Handbook of Mineralogy
Association: colemanite, ulexite, bakerite
Sources Handbook of Mineralogy
How it forms, step by step
A borate deposit forms in an evaporative/sedimentary setting, concentrating boron, calcium and silicon.
Sources Handbook of Mineralogy
Howlite precipitates and crystallises within the borate deposit.
Sources Handbook of Mineralogy
Crystals are tabular (to 1 cm), but nodular habit predominates; massive material is chalky to porcelaneous.
Sources Handbook of Mineralogy
Howlite is associated with borate minerals such as colemanite and ulexite.
Sources Handbook of Mineralogy
Link to appearance
Howlite is white (colourless in thin section), translucent in thin fragments, with a subvitreous, glimmering lustre and hardness 3.5; massive material is chalky to porcelaneous and resembles white gangue. Its white colour, low hardness and nodular habit are diagnostic.
Sources Handbook of Mineralogy
Timescale
The source states no absolute geological timescale for howlite formation.
Sources Handbook of Mineralogy
Supporting findings
Howlite occurs in borate deposits, most commonly as nodules.
Evidence grade BScope: Describes howlite's formation setting and habit.
Sources Handbook of Mineralogy
Howlite is associated with borate minerals such as colemanite, ulexite and bakerite.
Evidence grade BScope: Describes the association in borate deposits.
Sources Handbook of Mineralogy
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
Asia
- Susurluk, Balıkesir, Türkiye
Sources Handbook of Mineralogy
Europe
- Baljevac na Ibru, near Kraljevo, Serbiaprinted as Yugoslavia
Sources Handbook of Mineralogy
North America
- Black's quarry, Windsor, Hants County, Nova Scotia, Canada
Sources Mindat: Howlite · Handbook of Mineralogy
- Shore of Bras d'Or Lake, south of Iona, Cape Breton Island, Nova Scotia, Canada
Sources Handbook of Mineralogy
- Sterling Borax mine, Tick Canyon, near Lang, California, United States
Sources Handbook of Mineralogy
- Near Calico, San Bernardino County, California, United States
Sources Handbook of Mineralogy
- Near Ryan, Inyo County, California, United States
Sources Handbook of Mineralogy
- Borate mines north of Lockwood Valley, Ventura County, California, United States
Sources Handbook of Mineralogy
- Kramer deposit, Kern County, California, United States
Sources Handbook of Mineralogy
- Magdalena, Sonora, Mexico
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.
Where the name comes from
Howlite commemorates Henry How (1828–1879), a Canadian chemist, geologist and mineralogist at the University of King's College in Windsor, Nova Scotia, Canada, who was the first to describe this species.
Evidence grade BScope: The etymology explains the origin of a name only; it does not attest composition, locality, naturalness or treatment.
Sources Handbook of Mineralogy
How it is identified
Turquoise is often imitated by dyeing common minerals such as howlite or magnesite, and infrared (FTIR) spectra clearly distinguish turquoise from these imitations. A trade nomenclature table lists howlite as dyed almost always, with the dye classed as unstable.
Evidence grade AScope: Describes identification features reported by a laboratory or educational source; it is not a test that a reader can rely on, and any single piece can only be identified by a gemmological laboratory.
Sources G&G Winter 2024 · CIBJO Gemstone Book 2022
Other research findings
Howlite is a monoclinic borosilicate species with ideal composition Ca2B5SiO9(OH)5.
Evidence grade BScope: Species-level composition and crystal-system fact.
Sources Handbook of Mineralogy
Howlite is named for Henry How (1828-1879), the Canadian chemist, geologist and mineralogist who first described the species at Windsor, Nova Scotia.
Evidence grade BScope: Concerns naming and first-description history only.
Sources Handbook of Mineralogy
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- The source is a mineralogical data sheet and gives no absolute geological timescale for howlite formation.
- The source does not address treatment (e.g. dyeing to imitate turquoise) or health/safety claims for howlite; no such assertions are made here.
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
- Howlite
GB/T 16552—2017 Table A.2 “Howlite” · IMA Mineral List 2026-07 “Howlite”
Construction or treatment status
Natural identity; treatment status unknown
Treatments recorded for this material: Dyed
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
Howlite is Howlite; use "Howlite" for listings, and disclose any known treatments.
Evidence
- GB/T · Table A.2, row 羟硅硼钙石 (Howlite)
What this means for you
Before buying, check the recommended listing name "Howlite" 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
Howlite — 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
- treated
- Only after these treatments
- dyeing
Source & check 2026-09-25
- Source
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) (CIBJO): §8 Annex C, Howlite, p.57; §6.2 j (locator checked 2026-09-25)
- Fact checked on
- 2026-09-25
Howlite — care (chemicals): porous, so do not let it come into contact with coloured fluids; treatments with dye, oil, resin, wax or plastic are not permanent; keep it away from all solvents (including dish-washing liquids), chemicals and heat.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code c, special-care code k
- Treatment state
- treated
- Only after these treatments
- dyeing
Source & check 2026-09-25
- Source
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) (CIBJO): §8 Annex C, Howlite, p.57; §6.2 c, k (locator checked 2026-09-25)
- Fact checked on
- 2026-09-25
Howlite — care (wear): Some stones are prone to scratching due to low hardness. Wear them with care.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code a
- Treatment state
- treated
- Only after these treatments
- dyeing
Source & check 2026-09-25
- Source
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) (CIBJO): §8 Annex C, Howlite, p.57; §6.2 a (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
CleaningCare conclusions for Howlite come from the CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022); the cleaning, chemicals and wear conclusions all have the treatment state treated and apply only to dyed Howlite. Cleaning: dyed Howlite must not be cleaned ultrasonically. Chemicals: dyed Howlite is porous and should not come into contact with coloured fluids; treatments with dye, oil, resin, wax or plastic are not permanent, so keep it away from all solvents, including dish-washing liquids, and from chemicals and heat. Wear: dyed Howlite has low hardness and scratches easily, so wear it with care.
This table scrolls sideways on narrow screens.
| Question | Matching entries |
|---|---|
| Can it go in an ultrasonic or steam cleaner? | care (cleaning) |
| Contact with acids, alkalis and household chemicals | porous, so do not let it come into contact with coloured fluids; treatments with dye, oil, resin, wax or plastic are not permanent; keep it away from all solvents (including dish-washing liquids), chemicals and heat |
| Wearing limits (knocks, settings) | care (wear) |
Durability and wearing
Fracture
Nearly even and smooth (porcelaneous types)
Sources Handbook of Mineralogy
Treatments and identification leads
Registered treatmentsThe registered treatment for Howlite is dyeing, with the status treated, an effect stability of unstable and a prevalence of almost always. Identification cluesThe identification leads are uneven colour distribution under magnification, with colour often gathered in fractures, gaps between grains or surface depressions, and colour coming off when wiped with solvents such as acetone or anhydrous ethanol; the identification leads come from GB/T 16553—2017 Gems — Testing.
This table scrolls sideways on narrow screens.
| Treatment | Market frequency (CIBJO) | Stability (CIBJO) | GB/T 16552 category | JJA/AGL listing | Identification leads |
|---|---|---|---|---|---|
| dyeingStatus: treated | almost always | unstable | Treatment | — | See identification leads |
Where each treatment acts (schematics): Dyed
“—” means the cited source gives no value for that item, not “none”. Source: CIBJO Gemstone Book 2022 · GB/T 16553—2017; GB/T 16552—2017 Table B.1
Whether a treatment has to show in the name differs between the two rule sets (this site’s paraphrase):
- GB/T 16552—2017: a method classed as treatment has to be stated in the name itself — the method put before the name, or added in brackets after it; a method classed as optimization does not need to appear in the name, though one marked “Optimization (annotation required)” still has to be noted in the quality documents. Source: §5.4.2.1 a), b); §5.4.2.2 a)
- CIBJO Gemstone Book 2022: no longer splits treatments into ones that need specific disclosure and ones that need only general disclosure: every treatment is to be disclosed, and the seller tells the buyer which treatment was used and what special care it calls for. Source: §4.2.5 Note 2, §4.2.5.1, pp.14–15
What this table covers
What this page can give
- Registered treatments, their stability and how often they occur (see the table above)
- Identification leads for each treatment, for use when sending a stone for testing
VerifyNames, standards, technical facts, clauses and sources
Names
Standard and listing namesThe Chinese formal name for Howlite comes from GB/T 16552—2017 Table A.2; the suggested listing name is Howlite, and the mineralogical name is Howlite. Names in four languagesThe four-language names are the Simplified Chinese name, the Traditional Chinese name, the English name Howlite and the Japanese name. Institution usageOn authority wording, CIBJO lists Howlite (CIBJO Gemmological Laboratories Book 2024); the FTC text on file has no wording for this name (checked); GIA and Gem-A are unchecked. Where a body has no recorded wording, the entry's own English name is shown, which does not represent the body's position. Japanese namesA Japanese name is shown as the GSJ (Japan) formal name, but the wording of GSJ for this name is not yet verified by this site; what is shown is the entry's own Japanese name.
- GSJ (Japan) formal name
- ハウライト (not yet checked for this body — the entry's own Japanese name is shown)
- Chinese formal name
- 羟硅硼钙石 (GB/T 16552—2017 Table A.2)
- Mineralogical name
- Howlite
Four-language names
- 简体中文
- 羟硅硼钙石
- 繁體中文
- 羥硅硼鈣石
- English
- Howlite
- 日本語
- ハウライト
See also: Misleading and prohibited trade names · Supplementary name index
Classification
- Origin
- Natural materials
- Material domain
- Natural inorganic gem materials
- Browsing family
- Borate and tungstate minerals
- Identity tier
- Mineral species
- Mineral chemical class
- Borates and tungstates
- Construction or treatment status
- Natural identity; treatment status unknown
Treatments listed by standards
The “Howlite” row (p.17) of GB/T 16552—2017 Annex B, Table B.1 lists dyeing as the optimization or treatment for Howlite, with the effect of changing colour, classed as treatment. What Table B.1 notes and how each grade is defined are explained on this site's Gem treatments page.
GB/T 16552-2017, Annex B, Table B.1
Table B.1, row “Howlite” (p.17):
This table scrolls sideways on narrow screens.
| Method | Effect | Category |
|---|---|---|
| Dyeing | Changes colour | Treatment |
What Table B.1 is, and how the “see 5.4.1” grades are defined: see the GB/T 16552: optimization vs treatment page.
What it is and how it's identified
The chemical formula of Howlite is Ca2B5SiO9(OH)5, the phase is howlite, and the structure is a crystalline aggregate, usually compact and massive. Mohs hardness is 3–4, with no cleavage; this site notes that hardness alone is not enough to judge durability. Density is 2.45–2.58 g/cm³; the cited clause gives 2.58 with an allowed deviation of −0.13, from which the limits are derived. Optically it is an anisotropic aggregate, and birefringence cannot be measured in aggregates. The refractive index is 1.583–1.608; the cited clause gives 1.586–1.605 with an allowed deviation of ±0.003, from which the limits are derived; this site notes that the clause also has finer sub-ranges and the overall value is taken. The UV-Vis spectrum is not diagnostic, and the infrared spectrum shows the characteristic infrared absorption bands of howlite in the mid-infrared region; when untreated, long-wave UV fluorescence is brownish yellow and short-wave UV fluorescence weak to moderate orange, and the lustre is vitreous.
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
Howlite — 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
Howlite — composition (chemistry): Ca2B5SiO9 (OH) 5
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): §5.2.26 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Howlite — composition (phase): howlite
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Structure
Howlite — structure (overall): crystalline aggregate, typically compact and massive
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): §5.2.26 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Durability
Howlite — Mohs hardness: 3–4
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
- General note
- hardness only, not durability
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.26 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Howlite — cleavage: none
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): §5.2.26 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
For Howlite, the stability of dyeing is “unstable”.
CIBJO Gemstone Book 2022
- Treatment state
- treated
- Treatment
- dyeing
- Qualification
This says how well the treatment holds up, not how durable Howlite itself is.
- General note
- no durability verdict here
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Physical properties
Howlite — density: 2.45–2.58 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- Qualification
The clause we cite gives 2.58, with a stated tolerance of -0.13. The range shown here is worked out from that.
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.26 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Optical
Howlite — optic character: anisotropic aggregate
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): §5.2.26 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Howlite — refractive index: 1.583–1.608
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- Qualification
The clause we cite gives 1.586–1.605, with a stated tolerance of ±0.003. The range shown here is worked out from that.
- General note
- the clause has finer ranges
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.26 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Howlite — birefringence: not measurable on an aggregate
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): §5.2.26 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Howlite — pleochroism: not measurable on an aggregate
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): §5.2.26 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Howlite — fluorescence (long-wave UV): brown-yellow
GB/T 16553—2017
UV fluorescence (long-wave UV)brown-yellowDots are illustrative colours built from the colour names, not measured values
- 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): §5.2.26 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Howlite — fluorescence (short-wave UV): weak to moderate, orange
GB/T 16553—2017
UV fluorescence (short-wave UV)orangeweak–moderateDots are illustrative colours built from the colour names, not measured values
- 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): §5.2.26 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Howlite — spectrum (UV-visible): non-characteristic
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): §5.2.26 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Howlite — spectrum (infrared): diagnostic bands of howlite in the mid-IR
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): §5.2.26 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Howlite — magnification: dark grey or black web-like veins, compact massive structure.
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): §5.2.26 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
body colour2 sources compared
Howlite — body colour: White, often with dark grey and black spiderweb matrix.
CIBJO Gemmological Laboratories Book 2024
- Treatment state
- untreated
- Qualification
In chapter 7 of the CIBJO Gemmological Laboratories Book, the colour descriptions of Opal, Snowflake Obsidian, Onyx and other entries also name white or a whitish colour.
- General note
- colour alone is not identity
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Howlite — body colour: white or greyish white, usually with a network of dark grey and black veins.
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 Marble, Charoite, Chicken-blood Stone and other variety clauses also name white or a whitish colour.
- General note
- colour alone is not identity
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.26 (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
The two entries agree: white, often with dark grey and black veining (GB/T 16553—2017 also lists greyish white).
Quality factors
Howlite — quality factor (lustre): vitreous
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): §5.2.26 (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): 1.595 / 2.52; Closest values: 1Talc 1.569 / 2.5, 2Balin Stone 1.56 / 2.55, 3Bamboo Coral 1.57 / 2.65, 4Iolite 1.563 / 2.61, 5Freshwater Natural Pearl 1.605 / 2.72
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
Dyed Howlite can be recognised by uneven colour under magnification, with colour often gathered in fractures, grain boundaries or surface depressions, and by colour coming off when wiped with solvents such as acetone or anhydrous ethanol. These identification leads for dyeing are cited from GB/T 16553—2017; for identifying dyeing, GB/T 16553—2017 can only be used as a reference for Howlite and does not govern it directly. No synthetic counterpart of Howlite is available on the market. For Howlite in trade, the reported frequency of dyeing is “almost always”.
How far testing can go
Howlite that has undergone dyeing can be identified by the following features: Under magnification the colour is unevenly distributed and mostly concentrated in fissures, between grains or in surface hollows; wiping with acetone or absolute ethanol can lift the colour.
GB/T 16553—2017
- Treatment state
- colour treated
- Does this standard apply
- can be followed as a reference only
- Treatment
- dyeing
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.26 (dyeing) (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Howlite — 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
For Howlite in trade, the reported frequency of dyeing is “almost always”.
CIBJO Gemstone Book 2022
- Treatment state
- treated
- Treatment
- dyeing
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
Howlite has a clause-level definition in CIBJO Gemmological Laboratories Book 2024, registered under the entry name Howlite; the definition summary gives mineral species howlite and IMA status G, with the CIBJO wording quoted in full under Clause-level definitions on this page itself; the cross-check result is that it is defined directly by CIBJO and also appears in the GB/T annex. The IMA Mineral List entry registers the chemical formula of Howlite as Ca2SiB5O9(OH)5 with IMA status G; it is cross-checked against the RRUFF/IMA master mineral list, and the data are public domain.
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| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Howlite | 7.2.1.111 | White, often with dark grey and black spiderweb matrix, commonly dyed blue to imitate turquoise or lapis lazuli | Defined directly by CIBJO; also present in the GB/T annex. |
| Howlite | IMA Mineral List entry | Howlite Ca2SiB5O9(OH)5 G 1868 | 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 | Borate and tungstate minerals | Live |
| Treatments recorded for this material | Dyed | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Howlite 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.