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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
Muscovite
A mineral species basic name listed in GB/T 16552-2017 Annex A.2; muscovite beads may be aggregates or resin-stabilized. 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 Muscovite forms and what gives its colourFormation setting, process and timescale, each finding graded and sourced
- Treatments and enhancements of MuscoviteThe enhancements and treatments the GB/T and JJA/AGL tables list
- Caring for and wearing MuscoviteCleaning, heat, chemicals and light, as the cited sources give them; durability indicators and wearing advice
- Hardness, density and refractive index of MuscoviteEach value with its source and check date
- Muscovite 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 MuscoviteWhere the name comes from
- Listing and disclosing MuscoviteThe listing name to use; what must be disclosed before sale
- Standard clauses that define MuscoviteWhich 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
With the formula KAl2(Si3Al)O10(OH,F)2, muscovite is the pale mica most often encountered in the mica group. It counts as an important rock-forming mineral in gneisses, schists and phyllites and also appears in aplites, granite pegmatites and granites; under hydrothermal conditions it can develop from other minerals, and it may be detrital or authigenic. Its crystal structure — layered, with perfect cleavage — accounts for the elastic behaviour of its laminae, a property bound up with the mica-group structure.
Scope: Applies to the genesis, composition, occurrence and appearance of muscovite as a natural mica-group silicate mineral species; does not cover synthetic materials or products such as commercial mica paper.
Sources Handbook of Mineralogy
Where it forms
Phyllites, schists and gneisses (regionally metamorphosed rocks)
Sources Handbook of Mineralogy
Host rocks: aplites, granite pegmatites and granites
Sources Handbook of Mineralogy
Hydrothermal alteration settings and detrital/authigenic sedimentary settings
Sources Handbook of Mineralogy
How it forms, step by step
Aluminium-rich pelitic or felsic protoliths undergo metamorphic or magmatic-hydrothermal processes.
Sources Handbook of Mineralogy
Muscovite crystallizes during regional metamorphism, forming in phyllites, schists and gneisses.
Sources Handbook of Mineralogy
It crystallizes as a magmatic-hydrothermal mineral in granites, pegmatites and aplites.
Sources Handbook of Mineralogy
Muscovite may also form from other minerals under hydrothermal conditions, or occur as detrital/authigenic grains.
Sources Handbook of Mineralogy
Link to appearance
In thin section muscovite is usually colourless, though pale yellow, green or red-brown also occur; hand specimens may be rose-red, yellow, green, brown or gray. Its streak is white and the luster vitreous to pearly or silky, and the laminae bend and spring back.
Sources Handbook of Mineralogy
Timescale
The source states no absolute geological timescale for muscovite formation.
Sources Handbook of Mineralogy
Supporting findings
Muscovite ranks among the common rock-forming minerals, appearing in gneisses, schists and phyllites as well as in aplites, granite pegmatites and granites.
Evidence grade BScope: Describes muscovite's metamorphic and igneous occurrence; not laboratory synthesis.
Sources Handbook of Mineralogy
Under hydrothermal conditions muscovite may develop from other minerals; it can be detrital or authigenic.
Evidence grade BScope: Describes muscovite's hydrothermal and sedimentary origins; not its only origins.
Sources Handbook of Mineralogy
Muscovite is commonly associated with quartz, plagioclase, potassic feldspar, biotite, tourmaline and topaz.
Evidence grade BScope: Describes muscovite's typical associations; not all localities share them.
Sources Handbook of Mineralogy
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
Asia
- Slyudyanka, Lake Baikal, Russia
Sources Handbook of Mineralogy
- Nellore area, Andhra Pradesh, IndiaHoM: commercial (mica) deposits, not gem material
Sources Handbook of Mineralogy
Europe
- Murzinka, Ural Mountains, Russiaprinted as Mursinka
Sources Handbook of Mineralogy
- Bamble, Norway
Sources Handbook of Mineralogy
North America
- Mt. Mica, near Paris, Maine, United States
Sources Handbook of Mineralogy
- Pennsbury, Chester County, Pennsylvania, United States
Sources Handbook of Mineralogy
- Amelia, Virginia, United States
Sources Handbook of Mineralogy
- Black Hills, South Dakota, United States
Sources Handbook of Mineralogy
- Harding mine, Dixon, New Mexico, United States
Sources Handbook of Mineralogy
- Methuen and Calvin Townships, Ontario, Canada
Sources Handbook of Mineralogy
South America
- Minas Gerais, Brazil
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.
Where the name comes from
Muscovite's name comes from 'Muscovy glass', reflecting an occurrence in Russia's old province of Muscovy.
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
Other research findings
Muscovite has the formula KAl2(Si3Al)O10(OH,F)2 and belongs to the mica group.
Evidence grade BScope: Describes muscovite's composition and group; actual composition varies with substitution.
Sources Handbook of Mineralogy
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- The source states no absolute geological timescale for muscovite formation.
- The source does not quantify the specific P-T conditions of muscovite formation and recrystallization.
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
- Muscovite
GB/T 16552—2017 Table A.2 “Muscovite” · IMA Mineral List 2026-07 “Muscovite”
Construction or treatment status
Natural identity; treatment status unknown
Treatments recorded for this material: Filled / Fracture-filled (via parent material), Coated (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
Muscovite is Muscovite; use "Muscovite" for listings, and disclose any known treatments.
Evidence
- GB/T · Table A.2, row 白云母 (Muscovite)
What this means for you
Before buying, check the recommended listing name "Muscovite" 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
Muscovite — care (wear): a 2024 Journal of Gemmology paper on chrome muscovite notes that ordinary muscovite, being soft (about 2.5) with perfect cleavage, is generally not suited to jewellery use; the same paper concludes that the Sichuan cryptocrystalline green muscovite, toughened by its fine texture, suits some jewellery uses — the examples given are pendants, earrings and brooches.
The Journal of Gemmology (Blumentritt et al., 2024)
- Treatment state
- any treatment state
Source & check 2026-10-06
- Source
- F. Blumentritt, F. Notari, M. Becouze, M. Vigier, G. Zuber, C. Caplan & E. Fritsch, “Gem-quality Green Cryptocrystalline Muscovite (Fuchsite) from Ya’an Prefecture, Sichuan, China”, The Journal of Gemmology 39(1): 66–76 (2024) (archived excerpt: pp. 72–78 of the issue file): pp. 68, 74, 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
Numbers in curly braces, such as {111}, are crystallographic face symbols (Miller indices): each marks a set of crystal faces or cleavage planes. They are reproduced as written in the cited source.
Toughness
Laminae flexible and elastic; tough
Cleavage
{001} perfect; partings on {110}, {010}
Sources Handbook of Mineralogy
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.
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| 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 | — | — |
“—” means the cited source gives no value for that item, not “none”. Source: GB/T 16552—2017 Table B.1 (row for Mica Jade)
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 namesThe Chinese standard name for Muscovite comes from GB/T 16552—2017 Table A.2, and the suggested listing name is Muscovite. Trade and mineralogical namesThe mineralogical name is Muscovite, and the GSJ (Japan) has its own formal Japanese name. Names in four languagesNames are registered in four languages: Simplified Chinese, Traditional Chinese, English (Muscovite) and Japanese. Institution usageThe English name given under authority wording is Muscovite; of these bodies, the FTC text on file does not use the wording “Muscovite” (checked), and the wording of GIA, CIBJO and Gem-A is unchecked. Bodies without a recorded wording show the entry's own English name, which does not represent their position.
- GSJ (Japan) formal name
- 白雲母
- Chinese formal name
- 白云母 (GB/T 16552—2017 Table A.2)
- Mineralogical name
- Muscovite
Four-language names
- 简体中文
- 白云母
- 繁體中文
- 白雲母
- English
- Muscovite
- 日本語
- マスコバイト／白雲母
See also: Misleading and prohibited trade names · Supplementary name index
Classification
- Origin
- Natural materials
- Material domain
- Natural inorganic gem materials
- Browsing family
- Other silicate minerals
- Identity tier
- Mineral species
- Mineral chemical class
- Silicates
- Construction or treatment status
- Natural identity; treatment status unknown
Treatments listed by standards
Optimizations and treatments for Muscovite are applied from those listed for “Mica Jade” in GB/T 16552—2017, Annex B, Table B.1: filling and coating. Filling is graded under the cited standard, and coating is a treatment. The full content with effects is on the Mica Jade entry; what Table B.1 is and how the filling grades are defined are on the Gem treatments page.
GB/T 16552-2017, Annex B, Table B.1
Under the “Mica Jade” row of Table B.1: Filling Graded — see §5.4.1, Table 1; Coating Treatment. The full row, with the effect column, is on the Mica Jade 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 refractive index and body colour of Muscovite are registered for muscovite; all other items take values for mica jade (the whole class). For mica jade (the whole class): crystalline aggregate, commonly platy or scaly; Mohs hardness 2–3; density 2.2–3.4 g/cm³; optic character an anisotropic aggregate; birefringence not measurable on an aggregate; untreated, vitreous lustre, pearly on cleavage surfaces. The refractive index of Muscovite is 1.55–1.61; site note: this is the reading commonly obtained with the spot method, a typical value rather than an absolute limit. Body colour is white, green, yellow, grey, red, brown and similar, untreated; site note: the colour items in variety clauses such as brucite and quartzite jade also mention white or whitish tones.
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”.
Luminescence, UV-visible spectrum, infrared spectrum, magnification: these whole-class features are given in the cited clause for mica jade (the whole class), so they are not repeated on the Muscovite page; see the material facts on the Mica Jade entry.
Items below that name the class they cover give the cited clause’s value for that whole class, not a measurement of Muscovite (how to read class-level values).
Structure
Muscovite — structure (overall): crystalline aggregate, usually of flakes or scales.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- mica jade (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.38 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Durability
Muscovite — Mohs hardness: 2–3
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
- mica jade (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.38 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Physical properties
Muscovite — density: 2.2–3.4 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- mica jade (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.38 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Optical
Muscovite — optic character: anisotropic aggregate
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- mica jade (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.38 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Muscovite — refractive index: 1.55–1.61
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- Qualification
The clause we cite gives this as a value commonly read by the spot (distant-vision) method. It is a common value, not an absolute limit.
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.38 Refractive index · Muscovite (locator checked 2026-09-28)
- Fact checked on
- 2026-09-26
Muscovite — birefringence: not measurable on an aggregate
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- mica jade (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.38 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Muscovite — pleochroism: not measurable on an aggregate
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- mica jade (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.38 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Muscovite — optical effect (chatoyancy): seen; rare
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- mica jade (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.38 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Muscovite — body colour: white, green, yellow, grey, red, brown and other colours.
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 Brucite, Amber, Quartzite Jade 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): §5.2.38 Colour · Muscovite (locator checked 2026-09-28)
- Fact checked on
- 2026-09-26
- CIBJO definitions
- chatoyancy
Quality factors
Muscovite — quality factor (lustre): vitreous; cleavage surfaces show a pearly lustre.
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- mica jade (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.38 (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): 1.58 / 2.8; Closest values: 1Qingtian Stone 1.565 / 2.77, 2Natural Conch Pearl / Natural Melo Pearl 1.595 / 2.84, 3Brucite 1.57 / 2.89, 4Calcite 1.572 / 2.7, 5Giant Clam Shell 1.605 / 2.79
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
Muscovite has a clause-level definition in GB/T 16552-2017 Annex A, under the term Muscovite; the cross-check result is that it is listed directly by GB/T, and CIBJO carries no standalone entry under the same name. Muscovite is also registered in the IMA Mineral List entry, under the term Muscovite, with the definition Muscovite KAl2(Si3Al)O10(OH)2 A 1998 s.p.; it was cross-checked against the RRUFF/IMA master mineral list, which is public domain data.
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| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Muscovite | GB/T 16552-2017 Annex A | Muscovite | Listed directly by GB/T; CIBJO carries no standalone entry under the same name. |
| Muscovite | IMA Mineral List entry | Muscovite KAl2(Si3Al)O10(OH)2 A 1998 s.p. | 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.
Related-entry tree for Muscovite on this site: 2 entries listed by this site's parent-entry links; synthetic, treated and similar entries carry their recorded state after the name; this page (Muscovite) is marked.
- Muscovite
Sub-entries (1)
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| Page | Content | Status |
|---|---|---|
| Browsing family | Other silicate minerals | Live |
| Treatments recorded for this material | Filled / Fracture-filled (via parent material), Coated (via parent material) | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Muscovite 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.