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UnderstandWhat it is, what people ask, how far this page goes
Natural inorganic gem materials · Mineral species · Natural identity; treatment status unknown
Anorthite
The calcium end-member mineral species of the plagioclase series; gem-quality material is extremely rare, and it appears mostly as the end-member of the series. 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 Anorthite forms and what gives its colourFormation setting, process and timescale; where its colour and optical effects come from, each finding graded and sourced
- Treatments and enhancements of AnorthiteThe enhancements and treatments the GB/T and JJA/AGL tables list
- Caring for and wearing AnorthiteCleaning, heat, chemicals and light, as the cited sources give them
- Hardness, density and refractive index of AnorthiteEach value with its source and check date
- Anorthite 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?
- Listing and disclosing AnorthiteThe listing name to use; what must be disclosed before sale
- Standard clauses that define AnorthiteWhich 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
Anorthite (CaAl2Si2O8) is a tectosilicate mineral species of the feldspar group and the calcium end-member of the plagioclase solid-solution series: plagioclase is defined as a continuous solid solution between albite (NaAlSi3O8) and anorthite (CaAl2Si2O8), with composition expressed by An (mol.% anorthite), and anorthite lies at the calcium-rich end (about An90-100 by convention). It crystallizes from calcium-rich mafic magmas at relatively high temperature and occurs in plutonic, volcanic, and metamorphic rocks; within plagioclase from plutonic and metamorphic rocks, iron-oxide needles aligned crystallographically are present almost universally. Because standard gemological tests cannot separate feldspar varieties, variety identification usually requires XRD and chemical analysis.
Scope: Applies to the composition and crystallisation environment of natural anorthite as the calcium-rich end-member of the plagioclase solid solution; does not cover synthetic anorthite or treated material.
Sources G&G Summer 2025
Where it forms
Calcium-rich mafic magmas: calcic plagioclase crystallizes from calcium-rich melts at relatively high temperature.
Sources G&G Summer 2025
Plutonic and metamorphic rocks: plagioclase is a common rock-forming mineral there, often with oriented needle-like iron oxide inclusions.
Sources G&G Summer 2025
How it forms, step by step
In a calcium-rich silicate melt, calcium, aluminium, and silicon combine to crystallize calcic plagioclase (the high-An end) at relatively high temperature.
Anorthite and albite form a continuous solid-solution series, and the crystal composition lies at the calcium-rich end.
In plutonic and metamorphic rocks, calcic plagioclase commonly develops oriented needle-like iron oxide inclusions.
Variety identification requires XRD and chemical analysis rather than standard gemological tests.
Link to appearance
Anorthite is triclinic; calcic plagioclase is often dark and nearly opaque due to iron-oxide inclusions, with oriented needle inclusions and cleavage. Colour and inclusions do not indicate origin and require testing.
Sources G&G Fall 2013 · G&G Winter 2022 · G&G Summer 2025
- Oregon Sunstone: The Official State Gemstone of Oregon (Gems & Gemology, Fall 2013, Vol. 49, No. 3)
- Fluorescence Characteristics of Two Copper-Diffused Plagioclase Feldspars: Labradorite and Andesine (Gems & Gemology, Winter 2022, Vol. 58, No. 4)
- Structures Behind the Spectacle: A Review of Optical Effects in Phenomenal Gemstones and Their Underlying Nanotextures
Timescale
The sources give a 15-17 Ma age for associated basalts, but no absolute age or duration for anorthite crystallization itself.
Sources G&G Summer 2025
Related base materials
- Plagioclase solid-solution series (albite-anorthite): end-member-of | Anorthite is the calcium-rich end-member of the continuous plagioclase solid solution
- Feldspar group: member-of | Anorthite is a calcium aluminium silicate mineral species of the feldspar group
Supporting findings
Oriented needle-like iron oxide inclusions are especially common in more calcic plagioclase (andesine, labradorite, bytownite, and anorthite), and such needles are almost ubiquitous in plagioclase of plutonic and metamorphic rocks.
Evidence grade AScope: A general rule relating inclusions to plagioclase composition; it makes no deposit-specific claim for anorthite.
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
Asia
- Miyakejima Island, Tokyo, Japan
Sources Handbook of Mineralogy
Europe
- Monte Somma and Vesuvius, Campania, Italy
Sources Handbook of Mineralogy
- Mt. Monzoni, Val di Fassa, Trentino-Alto Adige, Italy
Sources Handbook of Mineralogy
North America
- Great Sitkin Island, Alaska, United States
Sources Handbook of Mineralogy
Seas and coasts
- Worldwide
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 the origin determination guide and the overview of recorded localities.
Causes of colour and optical effects
Plagioclase iridescence arises from submicron alternating calcic and sodic lamellae formed by solid-state exsolution (the Bøggild intergrowth): the calcic lamellae are generally thicker (about 70–200 nm) and the sodic ones thinner (about 50–100 nm), and interference occurs when the combined adjacent thickness is comparable to a visible-light wavelength. Anorthite sits at the calcic end (about An90–100), more calcic than the An46–60 range that denotes the most saturated labradorescence.
Evidence grade AScope: The cited sources place saturated labradorescence in the An46–60 range; for the An90–100 calcic end member the family mechanism can be extended in principle, but the sources do not list anorthite itself as a typical iridescent material and calcic plagioclase is often clouded by iron-oxide inclusions, so this is treated conservatively.
Plutonic, more calcic plagioclase is often clouded by iron-oxide inclusions, which weakens the brightness of reflections from internal lamellae; the cited sources place strong labradorescence at An46–60 and record no iridescence example for the An90–100 anorthite end member, so this entry describes anorthite's own labradorescence only conservatively.
Evidence grade BScope: An evidence-boundary note: the sources do not cover iridescence examples for the An90–100 end member, so no positive claim is made.
Other research findings
Anorthite is a feldspar-group mineral species and the calcium end-member of the plagioclase continuous solid-solution series; plagioclase is defined as a solid solution between albite (NaAlSi3O8) and anorthite (CaAl2Si2O8).
Evidence grade AScope: The definitional statement of the plagioclase series; anorthite and albite are the two end-members.
Anorthite has the formula CaAl2Si2O8 and is one of the three chemical end-members of feldspar (orthoclase, albite, anorthite).
Evidence grade AScope: A chemical end-member statement; real crystals may contain minor other components.
Plagioclase varieties are named by An (mol.% anorthite); anorthite lies at the calcium-rich end of the series, albite at the sodium-rich end (~An0), and labradorite is defined as An50-An70.
Evidence grade BScope: An example-based statement of the An naming; range boundaries are conventional rather than individually quantified by the source.
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- Sources give no absolute age or growth duration for anorthite crystallization itself.
- This record does not detail deposit-specific anorthite occurrences (e.g., anorthosite, metamorphosed carbonate rocks); it states the series membership and the general crystallization mechanism.
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
- Anorthite
GB/T 16552—2017 5.1.1 b) · CIBJO Gemmological Laboratories Book 2024 §7.2.1.18 “Anorthite”
Construction or treatment status
Natural identity; treatment status unknown
Treatments recorded for this material: Filled / Fracture-filled (via parent material), Coated (via parent material), Diffusion-treated (via parent material), Irradiated (via parent material)
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
Anorthite is Anorthite (IMA mineral species, plagioclase feldspar end-member); use "Anorthite" for listings, and disclose any known treatments.
What this means for you
Before buying, check the recommended listing name "Anorthite" 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
Anorthite — 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
- diffusion treatment
Source & check 2026-09-25
- Source
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) (CIBJO): §8 Annex C, Anorthite, p.52; §6.2 j (locator checked 2026-09-25)
- Fact checked on
- 2026-09-25
Anorthite — care (wear): cleaves or fractures easily or is brittle (e.g. rubbed facet edges); wear with care.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code b
- Treatment state
- treated
- Only after these treatments
- diffusion treatment
Source & check 2026-09-25
- Source
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) (CIBJO): §8 Annex C, Anorthite, p.52; §6.2 b (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
CleaningThe care entries for Anorthite come from the Anorthite row of Annex C of the CIBJO Gemstone Book (2022): diffusion-treated Anorthite must not be cleaned ultrasonically, and diffusion-treated Anorthite breaks easily, so wear it with care. The stated treatment state is treated and applies only to diffusion-treated Anorthite; it is not a general conclusion for the material as a whole. General careGeneral care that applies to all gems is given in the general care paragraph on the materials index page.
This table scrolls sideways on narrow screens.
| Question | Matching entries |
|---|---|
| Can it go in an ultrasonic or steam cleaner? | care (cleaning) |
| Wearing limits (knocks, settings) | cleaves or fractures easily or is brittle (e.g. rubbed facet edges); wear with care |
Treatments and identification leads
One row per treatment, with three standards side by side: how often it occurs and how stable it is (CIBJO), its category in GB/T 16552—2017 Table B.1 (this site's paraphrase) and how the JJA/AGL 2025 table lists it. Each CIBJO value links to its entry under “Testing and market”, where the wording and source are given in full.
This table scrolls sideways on narrow screens.
| Treatment | Market frequency (CIBJO) | Stability (CIBJO) | GB/T 16552 category | JJA/AGL listing | Identification leads |
|---|---|---|---|---|---|
| Filling | — | — | Graded — see §5.4.1, Table 1 | — | — |
| Coating | — | — | Treatment | — | — |
| Diffusion | — | — | Treatment | — | — |
| Irradiation | — | — | Treatment | — | — |
“—” means the cited source gives no value for that item, not “none”. Source: GB/T 16552—2017 Table B.1 (row for Feldspar)
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
VerifyNames, standards, technical facts, clauses and sources
Names
Standard and listing namesAnorthite is not listed in Annex A of GB/T 16552—2017; as that standard allows mineral or material names not listed in Annex A to be used directly, Anorthite can be used as the name, and the suggested listing name is Anorthite. Trade and mineralogical namesThe mineralogical name is Anorthite, the calcium end-member species of the plagioclase series, listed as Anorthite in the IMA mineral list. Names in four languagesThe four-language names are the Simplified and Traditional Chinese names, English Anorthite and the Japanese names, with the GSJ (Japan) formal name written in kanji. Institution usageFor authority wording, the CIBJO Gemmological Laboratories Book 2024 records Anorthite; the FTC text on file has no wording for this name (checked); GIA and Gem-A are unchecked, and bodies without a recorded wording show the entry's own English name, which does not represent their position.
- GSJ (Japan) formal name
- 灰長石
- Mineral / material name (not in GB/T 16552 Annex A; usable directly)
- 钙长石 (GB/T 16552—2017 §5.1.1 b))
- Mineralogical name
- Anorthite (IMA mineral species, plagioclase feldspar end-member)
Four-language names
- 简体中文
- 钙长石
- 繁體中文
- 鈣長石
- English
- Anorthite
- 日本語
- アノーサイト／灰長石
See also: Misleading and prohibited trade names · Supplementary name index
Classification
- Origin
- Natural materials
- Material domain
- Natural inorganic gem materials
- Browsing family
- Feldspar materials
- Identity tier
- Mineral species
- Mineral chemical class
- Silicates
- Construction or treatment status
- Natural identity; treatment status unknown
Treatments listed by standards
GB/T 16552-2017, Annex B, Table B.1
Under the “Feldspar” row of Table B.1: Filling Graded — see §5.4.1, Table 1; Coating Treatment; Diffusion Treatment; Irradiation Treatment. The full row, with the effect column, is on the Feldspar page.
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 composition of Anorthite is registered under plagioclase (the whole series), between NaAlSi3O8 and CaAl2Si2O8; the cited clauses for fluorescence, UV-Vis spectrum, infrared spectrum and magnification are written for feldspar (the whole mineral group), so see the material facts in the feldspar entry. Structure, durability, physical and optical values are taken from feldspar (the whole mineral group) and are not data measured on anorthite alone: crystalline, with tabular or short prismatic crystals, commonly showing Carlsbad, polysynthetic and cross-hatched twinning; Mohs hardness 6–6.5; two sets of perfect cleavage; density 2.55–2.75 g/cm³; optically anisotropic, biaxial, positive or negative; refractive index 1.508–1.572, birefringence 0.005–0.01; pleochroism usually absent (treatment status: untreated); iridescence, cat's-eye effect, star effect and aventurescence may be seen; quality factor (lustre) vitreous (treatment status: untreated). For density, refractive index and birefringence, this site notes that the clause also has finer sub-ranges and the overall value is taken.
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 feldspar (the whole mineral group), so they are not repeated on the Anorthite page; see the material facts on the Feldspar entry.
Items below that name the class they cover give the cited clause’s value for that whole class, not a measurement of Anorthite (how to read class-level values).
Definition
Anorthite — 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
Anorthite — composition (chemistry): plagioclase: NaAlSi3O8–CaAl2Si2O8.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- plagioclase (the whole series)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 Chemical composition · Plagioclase (locator checked 2026-09-28)
- Fact checked on
- 2026-09-26
Structure
Anorthite — structure (overall): crystalline
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Anorthite — structure (crystal system): Moonstone and amazonite belong to the monoclinic or triclinic system; sunstone and labradorite are triclinic.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Anorthite — structure (crystal habit): Crystals are tabular or stubby prisms; Carlsbad, polysynthetic and gridiron (cross-hatched) twinning are common.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Durability
Anorthite — Mohs hardness: 6–6.5
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
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Anorthite — cleavage: two directions of perfect cleavage
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Physical properties
Anorthite — density: 2.55–2.75 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
- General note
- the clause has finer ranges
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Optical
Anorthite — optic character: biaxial and anisotropic; optic sign may be either positive or negative.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Anorthite — refractive index: 1.508–1.572
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
- General note
- the clause has finer ranges
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Anorthite — birefringence: 0.005–0.01
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
- General note
- the clause has finer ranges
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Anorthite — pleochroism: usually absent
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Anorthite — optical effect (iridescence): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Anorthite — optical effect (chatoyancy): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Anorthite — optical effect (asterism): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Anorthite — optical effect (aventurescence): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
- CIBJO definitions
- chatoyancy, asterism, aventurescence
Quality factors
Anorthite — quality factor (lustre): vitreous
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (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): 1.54 / 2.65; Closest values: 1Charoite 1.554 / 2.66, 2Changhua Stone 1.56 / 2.6, 3Shoushan Stone 1.56 / 2.7, 4Balin Stone 1.56 / 2.55, 5Bamboo Coral 1.57 / 2.65
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
Clause-level definitions
Anorthite is defined directly in CIBJO Gemmological Laboratories Book 2024 under the entry name Anorthite, describing it as the calcium-rich endmember of the plagioclase series; the cross-check result is that it is defined directly by CIBJO, while no identically named English entry was found in the GB/T annex. The IMA Mineral List entry likewise lists it as Anorthite, giving the chemical formula Ca(Al2Si2O8) and the notation G 1823, cross-checked against the RRUFF/IMA master mineral list; this is public domain data.
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| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Anorthite | 7.2.1.18 | Anorthite is the calcium-rich endmember of the plagioclase series. It is a rare composition of plagioclase, see bytownite, labradorite, spectrolite, sunstone | Defined directly by CIBJO; no identically named English entry was found in this edition of the GB/T annex. |
| Anorthite | IMA Mineral List entry | Anorthite Ca(Al2Si2O8) G 1823 | 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.
- 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 | Feldspar materials | Live |
| Treatments recorded for this material | Filled / Fracture-filled (via parent material), Coated (via parent material), Diffusion-treated (via parent material), Irradiated (via parent material) | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Anorthite 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.