On this page
UnderstandWhat it is, what people ask, how far this page goes
Natural inorganic gem materials · Trade name: colour / appearance variety · Natural identity; treatment status unknown
Pietersite
A trade name for a brecciated quartz aggregate with a cat's-eye effect; its definition, structure and origin are used inconsistently on the market. 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 Pietersite forms and what gives its colourFormation setting, process and timescale; where its colour and optical effects come from, each finding graded and sourced
- Hardness, density and refractive index of PietersiteEach value with its source and check date
- Pietersite 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?
- Listing and disclosing PietersiteThe 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
Pietersite is a chatoyant siliceous aggregate that has been brecciated and described as a brecciated form of tiger’s-eye, in which the parent material is quartz in its chalcedony form. The crocidolite fibres supply the chatoyancy, and the silica present is chalcedony rather than columnar quartz. Genetically it sets itself apart from South African tiger’s-eye: one hypothesis holds that it originated as a solution breccia, the crocidolite fibres being generated by late-stage reactions between hematite and chalcedony within a sodium-rich fluid. According to reports, Namibia and China are its only sources.
Scope: Covers an overview of the formation of pietersite (a trade name for brecciated cat's-eye quartz aggregates); its origin follows the "solution breccia" hypothesis from peer-reviewed/institutional sources.
Sources G&G Winter 2010 · G&G Summer 2025
Where it forms
Namibia and China (reportedly the main sources); formed in a brecciated siliceous system in a sodic fluid.
Sources G&G Winter 2010 · G&G Summer 2025
How it forms, step by step
A crocidolite-bearing siliceous system is brecciated.
Crocidolite fibres are produced by late-stage reactions that occur in a sodium-rich fluid between hematite and chalcedony.
Aligned fibers are encapsulated by silica, producing chatoyancy.
Link to appearance
The cat's-eye appearance comes from reflection off aligned crocidolite fibers, an optical mechanism; an appearance name alone cannot prove origin or material class.
Sources G&G Winter 2010 · G&G Summer 2025
Timescale
The sources in this record give no absolute age or growth duration for pietersite.
Sources G&G Summer 2025
Related base materials
- quartz: The siliceous host of pietersite is a quartz-group mineral (chalcedony)
- tiger's-eye: Pietersite is generally described as a brecciated variety of tiger's eye
Supporting findings
One hypothesis holds that pietersite originated as solution breccias, the crocidolite fibres being generated by late-stage reactions that took place between hematite and chalcedony within a sodium-rich fluid.
Evidence grade AScope: One of the proposed hypotheses (solution breccia); explicitly labelled as theorized.
According to reports, Namibia and China are its only sources.
Evidence grade AScope: Stated conservatively as 'reportedly'; refers to the main sources and may not be exhaustive.
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
Africa
- Outjo area (Kuraman district), Kunene, NamibiaChina and Namibia are the only known gem-quality sources; Namibian minable stock was reported largely depleted by 1996
Sources Gems & Gemology Winter 2010 · Mindat: Pietersite
Asia
- Xichuan County, Nanyang, Henan, ChinaChina and Namibia are the only known gem-quality sources
Sources Gems & Gemology Winter 2010
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 the origin determination guide and the overview of recorded localities.
Causes of colour and optical effects
Pietersite's cat's-eye band is produced by oriented crocidolite (riebeckite) fibres: because the fibres run parallel, light scattering and reflection off them is collected by a cabochon into a single bright line lying perpendicular to the fibre length, which shifts as the light source moves. The direction of the eye therefore follows the fibre orientation rather than the body colour of the material.
Evidence grade AScope: Applies to pietersite bearing parallel crocidolite fibres; the origin of the fibres and provenance remain debated, and the mechanism does not establish any sample's locality, naturalness, or treatment.
Sources GIA Tiger's-Eye Quartz · G&G Summer 2025
Other research findings
The silica composing pietersite is chalcedony rather than columnar quartz; its chatoyancy is caused by crocidolite fibers.
Evidence grade AScope: Describes material composition and the chatoyancy mechanism; no other genetic hypothesis.
Pietersite is generally described as a brecciated variety of tiger's-eye; one study proposes its petrogenesis is quite different from South African tiger's-eye, so this record does not transfer tiger's-eye's pseudomorphism/crack-seal mechanism to pietersite.
Evidence grade AScope: Defines the relationship to tiger's-eye and flags the different petrogenesis; does not claim a shared mechanism.
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- Pietersite is a trade/variety name, not an independent species; parent material is quartz (chalcedony).
- The solution-breccia origin is labelled as theorized, not settled.
- No absolute age or growth duration is given.
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
- Pietersite
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
"Pietersite" is a market name rather than a mineral species name; before using it, verify: Trade name rather than a mineralogical species name.
What this means for you
Before buying, check the recommended listing name "Pietersite" and any disclosed treatments on this page, and ask the seller for a grading report if in doubt.
Known uncertainty
- This entry's exact material identity is not fully settled.
- See “Disclosure and cautions” above
- Last reviewed
- 2026-09-01
Trade-name ruling
- Trade name rather than a mineralogical species name.
- Suggested listing name
- Pietersite
Care and wear
No care facts are recorded for this entry itself. Its parent material has care records: see Tiger’s Eye.
VerifyNames, standards, technical facts, clauses and sources
Names
Besides Pietersite, the name register records "Pietersite", for which no restriction on use as a name is recorded.
Standard and listing namesPietersite is not included in GB/T 16552—2017; when naming under GB/T 16552—2017, the basic name must be determined by testing; the suggested listing name given by this site is Pietersite. Trade and mineralogical namesThe trade name or synonym of Pietersite is Pietersite, listed in the name register as an English market name, on the basis of this site's ruling rather than any clause, with the identity tier trade name (colour or appearance variety). As for the mineralogical name, Pietersite is described as a brecciated quartz aggregate showing chatoyancy, and is a trade name. Names in four languagesNames are given in Simplified Chinese, Traditional Chinese, English (Pietersite) and Japanese; for Japan, the Japanese name shown is the entry's own, and the GSJ (Japan) wording for this name is not yet verified by this site. Institution usageOn authority wording, checking shows that the FTC and CIBJO texts on file contain no wording for this name; the wording of GIA and Gem-A is not yet verified by this site, and bodies without a recorded wording show the entry's own English name, which does not represent the position of any body.
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) | ||||
| PietersiteEnglish | market name | matched automatically | no restriction recorded | editorial ruling (no clause cited) |
How each authority words this name: see Names › Authority wording.
- GSJ (Japan) formal name
- ピーターサイト (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)
- basic name to be determined by testing (GB/T 16552—2017 §5.1.1 c))
- Mineralogical name
- Brecciated chatoyant quartz aggregate; trade name
Four-language names
- 简体中文
- 彼得石
- 繁體中文
- 彼得石
- English
- Pietersite
- 日本語
- ピーターサイト
See also: Misleading and prohibited trade names · Supplementary name index
Classification
- Origin
- Natural materials
- Material domain
- Natural inorganic gem materials
- Browsing family
- Quartz and chalcedony materials
- Identity tier
- Trade name: colour / appearance variety
- Mineral chemical class
- Silicates
- Construction or treatment status
- Natural identity; treatment status unknown
What it is and how it's identified
Among the registered material facts for Pietersite, structure and the physical and optical items take the cited clause's values for silicified jade (including silicified asbestos, petrified wood and silicified coral, the whole class), not data measured for Pietersite on its own. Under the clause for silicified jade (the whole class), Pietersite has a structure (overall) of a crystalline aggregate, Mohs hardness 5–7, cleavage none, density 2.48–2.85 g/cm³, optic character anisotropic aggregate, refractive index 1.544–1.553 (this site's general note: the clause has finer ranges and the overall value is used) and birefringence not measurable on an aggregate; pleochroism is not measurable on an aggregate, for the untreated state; the optical effect chatoyancy may be seen; and lustre (as a quality factor) is vitreous, greasy or waxy on fractures, with silky lustre also seen in silicified asbestos, for the untreated state. Chemical composition, fluorescence, spectra and magnification are recorded under the clause for silicified jade (the whole class); see the material facts on the silicified jade 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 silicified jade (the whole class), so they are not repeated on the Pietersite page; see the material facts on the Silicified Jade entry.
Items below that name the class they cover give the cited clause’s value for that whole class, not a measurement of Pietersite (how to read class-level values).
Structure
Pietersite — structure (overall): crystalline aggregate
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- silicified jade (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.6 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Durability
Pietersite — Mohs hardness: 5–7
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
- silicified jade (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.6 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Pietersite — cleavage: none
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- silicified jade (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.6 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Physical properties
Pietersite — density: 2.48–2.85 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- silicified jade (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.6 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Optical
Pietersite — optic character: anisotropic aggregate
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- silicified jade (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.6 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Pietersite — refractive index: 1.544–1.553
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- silicified jade (the whole class)
- General note
- the clause has finer ranges
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.6 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Pietersite — birefringence: not measurable on an aggregate
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- silicified jade (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.6 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Pietersite — pleochroism: not measurable on an aggregate
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- silicified jade (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.6 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Pietersite — optical effect (chatoyancy): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- silicified jade (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.6 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
- CIBJO definitions
- chatoyancy
Quality factors
Pietersite — quality factor (lustre): vitreous; greasy or waxy on the fracture; silicified asbestos may also show a silky luster.
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- silicified jade (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.6 (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): 1.548 / 2.67; Closest values: 1Agate 1.537 / 2.63, 2Shoushan Stone 1.56 / 2.7, 3Changhua Stone 1.56 / 2.6, 4Bamboo Coral 1.57 / 2.65, 5Synthetic Beryl 1.57 / 2.69
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
Evidence and sources
Authority basis and clause sources
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.
Related-entry tree for Quartz on this site: 74 entries listed by this site's parent-entry links; synthetic, treated and similar entries carry their recorded state after the name; this page (Pietersite) is marked.
- Quartz
Sub-entries (57)
- Agate
Sub-entries (1)
- Amethyst
- Ametrine
- Aventurine Quartz
- Aventurine Quartz / Green Aventurine
- Banded Agate
- Black Agate
- Bloodstone / Heliotrope
- Blue Lace Agate
- Carnelian
- Chalcedony
Sub-entries (2)
- Chrysoprase
- Citrine
- Clear Quartz / Rock Crystal
- Coated Quartz
- Colourless to White Quartz (brand name: Azeztulite)
- Crazy Lace Agate
- Dendritic Agate
- Dyed Agate (Treated: dyed)
- Elestial Quartz / Skeletal Quartz
- Eye Agate
- Flower Agate / Cherry Blossom Agate
- Green Quartz
- High-clarity quartz with golden needle-like inclusions
- Included Quartz
- Jasper
Sub-entries (1)
- Madeira Citrine
- Malachite Agate
- Morion / very dark Smoky Quartz
- Moss Agate
- Moss Chalcedony
- Multi-inclusion Quartz
- Onyx (banded chalcedony)
- Phantom Quartz
- Prase
- Prasiolite / Green Quartz
- Quartz Cat’s-eye
- Quartz claimed to be from the Himalayas
- Quartz Crystal
- Quartz with dark needle-like inclusions
- Quartz with fine fibrous inclusions
- Quartz with flower-like inclusions
- Quartz with golden needle-like inclusions
- Quartz with green needle-like inclusions
- Quartzite Jade
- Quartzose Jade
- Red Agate
- Rock Crystal
- Rose Quartz
- Rutilated Quartz
- Sard
- Sardonyx
- Silicified Asbestos
Sub-entries (2)
- Hawk’s Eye
- Tiger’s Eye
Sub-entries (1)
- Pietersite
- Smoky Quartz
- Smoky Quartz (brown variety)
- Strawberry Quartz
- Yellow-green Quartz
- Agate
This table scrolls sideways on narrow screens.
| Page | Content | Status |
|---|---|---|
| Browsing family | Quartz and chalcedony materials | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Pietersite 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.