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
Moss Chalcedony
Chalcedony with moss-like inclusions; it is a neighbouring concept to Moss Agate, and the naming boundary between the two varies by 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 Moss Chalcedony forms and what gives its colourFormation setting, process and timescale; where its colour and optical effects come from, each finding graded and sourced
- How to identify Moss ChalcedonyIdentification points from the research literature; how far lab testing can go
- Treatments and enhancements of Moss ChalcedonyThe enhancements and treatments the GB/T and JJA/AGL tables list
- Hardness, density and refractive index of Moss ChalcedonyEach value with its source and check date
- Moss Chalcedony 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 Moss ChalcedonyThe 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
Moss agate is a trade name for chalcedony (microcrystalline quartz) containing moss-like (dendritic/floccose) green or dark inclusions; its matrix genesis follows the chalcedony parent material: silica-rich fluids fill voids or fissures in the host rock cyclically from the rim toward the centre, precipitating layer by layer. The 'moss' is not organic but a mineral phase enclosed in the silica matrix; chalcedony can enclose many solids, including needle-like Fe-compound inclusions, Cu sulfides, Ti oxides, calcite and organic matter, incorporated under post-magmatic hydrothermal or hypogenic conditions. The visible green can be produced by a greenish mineral phase between quartz grains (located along grain boundaries), distributed with the matrix during crystallization to create the moss-like appearance. Chalcedony-type material may also be dyed, so natural and treated colour must be distinguished.
Scope: Used to explain how moss chalcedony inherits the filling origin of chalcedony, and that its "moss" consists of mineral inclusions in a siliceous matrix rather than organisms; the specific inclusion minerals and pattern mechanism must be identified separately.
Sources G&G Fall 2013 · G&G Spring 1982 · G&G Winter 2015
- Agates from Morocco: Gemological Characteristics and Proposed Origin (Gems & Gemology, Fall 2013, Vol. 49, No. 3)
- The Natural Formation and Occurrence of Green Quartz (Gems & Gemology, Spring 1982, Vol. 18, No. 1)
- A New Natural-Color Bluish Green Chalcedony (Gems & Gemology, Winter 2015, Vol. 51, No. 4)
Where it forms
Voids and vesicles in volcanic rock (geodes, vugs) and fissures in sedimentary rocks, where silica-rich fluids fill them cyclically to form the chalcedony matrix.
Sources G&G Fall 2013 · G&G Spring 1982
Later hydrothermal and hypogenic settings, where solid inclusions such as Fe compounds, Cu sulfides, Ti oxides, calcite and organic matter are incorporated into the silica matrix.
Sources G&G Fall 2013
How it forms, step by step
Silica-rich fluids enter voids or fissures in the host rock and fill them cyclically from the rim toward the centre.
Silica precipitates layer by layer as fibrous microcrystalline quartz (chalcedony), forming the matrix.
Mineral phases (needle-like Fe-compound inclusions, Cu sulfides, Ti oxides, calcite, organic matter) are incorporated into the matrix under post-magmatic hydrothermal or hypogenic conditions.
Inclusions such as a greenish mineral phase along quartz grain boundaries appear with the matrix, producing the moss-like pattern; chalcedony-type material may also be dyed to enhance colour.
Link to appearance
Moss-, dendrite- or floccose-like distributions in a translucent chalcedony matrix, mostly green/dark; the pattern is formed by mineral inclusions (a greenish phase along grain boundaries, Fe compounds, etc.), not by biological growth.
Sources G&G Winter 2015 · G&G Fall 2013
Timescale
Sidi Rahal agate (chalcedonic) crystallization lasted millions of years and proceeded in stages; the moganite-to-low-quartz transformation generally occurs over tens of millions of years and can serve as a relative age indicator.
Sources G&G Fall 2013 · G&G Spring 1982
Related base materials
- Chalcedony: inclusion variety | Moss chalcedony is a commercial name for chalcedony containing moss-like inclusions
- Agate: Chalcedony (agate) with inclusion patterns
Supporting findings
Chalcedony can enclose many solid minerals and organic matter (Fe compounds, Cu sulfides, Ti oxides, calcite, organic matter), incorporated into the matrix under post-magmatic hydrothermal or hypogenic conditions.
Evidence grade AScope: A general account of solid-inclusion incorporation in chalcedony, from a Moroccan agate study.
Moss agate inherits the chalcedony parent-material genesis: silica-rich fluids fill voids or fissures cyclically from rim to centre, precipitating microcrystalline quartz layer by layer.
Evidence grade AScope: Describes matrix filling; the specific mechanism forming the moss-like pattern is not covered by the cited sources.
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
North America
- Yellowstone River, Montana, United StatesCollectible moss agate; title of a G&G abstract page
Sources Gems & Gemology Summer 2013
These are localities recorded by authoritative sources, not an origin finding for any individual piece. The CIBJO Gemstone Book (2022, §4.2.3) says a place of origin names where a gem was mined or harvested, is a matter of opinion, does not imply a level of quality, and that cutting, processing or exporting centres must not be used to imply origin. See how far testing can go on this page, the origin determination guide and the overview of recorded localities.
Causes of colour and optical effects
Chalcedony may take on a green hue when a green mineral phase sits at the boundaries between individual quartz grains.
Evidence grade BScope: This observation comes from a different bluish green chalcedony sample and may not represent moss agate; the green cause needs case-by-case identification.
Sources G&G Winter 2015
How it is identified
For moss chalcedony, colour and banding by themselves do not reveal whether the hue is natural or produced by dyeing or heating, so visual appearance cannot settle naturalness or treatment; a trustworthy identification and any treatment ruling call for instrumental examination at a qualified gem laboratory, and this entry is no basis for self-testing.
Evidence grade AScope: Appearance cannot replace identification; naturalness, dyeing or heat treatment must be determined at a qualified gem laboratory, and this entry is not a self-testing basis.
Sources G&G Summer 2014 · CIBJO Gemstone Book 2022
Other research findings
Moss agate is a trade name for chalcedony (microcrystalline quartz) containing moss-like (dendritic) inclusions; the pattern is a mineral feature, not biological.
Evidence grade BScope: 'Moss-like' is a trade descriptor; its exact definition and the common inclusion minerals are not defined in the cited source.
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- The authoritative sources do not specifically discuss moss agate; the exact mineral species of the 'moss' inclusions (e.g. chlorite, hornblende) and the mechanism forming the dendritic pattern are not covered by the cited sources.
- The green colouring factor is only extrapolated from another chalcedony sample and cannot be used to determine moss agate's green cause.
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
- Moss Chalcedony
GB/T 16552—2017 5.1.1 c)
Construction or treatment status
Natural identity; treatment status unknown
Treatments recorded for this material: Heated / Heat-treated (via parent material), Filled / Fracture-filled (via parent material), Dyed (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
"Moss Chalcedony" is a market name rather than a mineral species name; before using it, verify: Industry-wide term that does not denote a single species.
What this means for you
Before buying, check the recommended listing name "Moss Chalcedony" 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
- Industry-wide term that does not denote a single species.
- Suggested listing name
- Moss Chalcedony
Care and wear
No care facts are recorded for this entry itself. Its parent material has care records: see Quartz.
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 |
|---|---|---|---|---|---|
| Heating | — | — | Optimization | — | — |
| Filling | — | — | Graded — see §5.4.1, Table 1 | — | — |
| Dyeing | — | — | Optimization | — | — |
“—” means the cited source gives no value for that item, not “none”. Source: GB/T 16552—2017 Table B.1 (row for Chalcedony)
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
Besides Moss Chalcedony, the name register records "Moss chalcedony", for which no restriction on use as a name is recorded.
Trade and mineralogical namesMoss Chalcedony is a trade name, not a mineralogical species name; GB/T 16552—2017 does not include it, so Moss Chalcedony is labelled with the Table A.2 basic name chalcedony, and under the GB/T 16552—2017 naming rules a trade name should not be used on its own: the label should give the basic name of the material followed by the note trade name: Moss Chalcedony. Recommended listing nameThe suggested listing name is Moss Chalcedony, the trade name/synonym is Moss chalcedony, and the mineralogical name is chalcedony with moss-like inclusions. Names in four languagesFour-language names are given in Simplified Chinese, Traditional Chinese, English (Moss Chalcedony) and Japanese; the wording of Japan's GSJ for this material is not yet verified by this site, and the Japanese name is the entry's own. Institution usageOn authority wording, the FTC and CIBJO texts on file have no wording for Moss Chalcedony (checked), and CIBJO Gemmological Laboratories Book 2024 does not contain Moss Chalcedony; GIA and Gem-A are unchecked; bodies without a recorded wording show the entry's own English name, which does not represent their position.
Name register
Every name recorded for this entry, with how it is classified, whether it may be matched to this entry automatically, whether it may be used as a product name, and the clause it rests on.
This table scrolls sideways on narrow screens.
| Name | Type | Matching | Use as a name | Basis |
|---|---|---|---|---|
| no restriction recorded (1) | ||||
| Moss chalcedonyEnglish | 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
- モスカルセドニー (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)
- 玉髓 (GB/T 16552—2017 Table A.2, row “Chalcedony(Agate/Jasper)”)
- Mineralogical name
- Chalcedony with moss-like inclusions
Four-language names
- 简体中文
- 苔藓玉髓
- 繁體中文
- 苔蘚玉髓
- English
- Moss Chalcedony
- 日本語
- モスカルセドニー
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
Treatments listed by standards
The treatment classification of Moss Chalcedony is applied by this site from the "Chalcedony (Agate/Jasper)" row of GB/T 16552—2017 Annex B, Table B.1: heating is an optimization; filling is graded; dyeing is an optimization. What Table B.1 is, and how the filling grades are defined, are on the Gem treatments page; the full row with the effect column is on the Chalcedony page.
GB/T 16552-2017, Annex B, Table B.1
Under the “Chalcedony (Agate/Jasper)” row of Table B.1: Heating Optimization; Filling Graded — see §5.4.1, Table 1; Dyeing Optimization. The full row, with the effect column, is on the Chalcedony 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 registered material facts for Moss Chalcedony take the cited clause's values for chalcedony, including agate and jasper (the whole class): structure a cryptocrystalline aggregate, compact and massive, and may also form spherulitic, radiating or microfibrous aggregates; Mohs hardness 5–7; cleavage none; density 2.5–2.77 g/cm³; optic character anisotropic aggregate; refractive index 1.535–1.539 (this site notes the clause has finer sub-ranges and the overall value is taken); birefringence not measurable for an aggregate; iridescence visible and chatoyancy visible; untreated, pleochroism not measurable for an aggregate and the quality factor (lustre) vitreous to greasy. Chemical composition, luminescence, UV-visible spectrum, infrared spectrum and magnification are written for chalcedony, including agate and jasper (the whole class); see the Chalcedony 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 chalcedony, including agate and jasper (the whole class), so they are not repeated on the Moss Chalcedony page; see the material facts on the Chalcedony entry.
Items below that name the class they cover give the cited clause’s value for that whole class, not a measurement of Moss Chalcedony (how to read class-level values).
Structure
Moss Chalcedony — structure (overall): a cryptocrystalline aggregate, dense and massive in habit; it may also form spherulitic, radial or finely fibrous aggregates.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- chalcedony, including agate and jasper (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Durability
Moss Chalcedony — 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
- chalcedony, including agate and jasper (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Moss Chalcedony — cleavage: none
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- chalcedony, including agate and jasper (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Physical properties
Moss Chalcedony — density: 2.5–2.77 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- chalcedony, including agate and jasper (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Optical
Moss Chalcedony — optic character: anisotropic aggregate
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- chalcedony, including agate and jasper (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Moss Chalcedony — refractive index: 1.535–1.539
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- chalcedony, including agate and jasper (the whole class)
- General note
- the clause has finer ranges
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Moss Chalcedony — birefringence: not measurable on an aggregate
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- chalcedony, including agate and jasper (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Moss Chalcedony — pleochroism: not measurable on an aggregate
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- chalcedony, including agate and jasper (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Moss Chalcedony — optical effect (iridescence): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- chalcedony, including agate and jasper (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Moss Chalcedony — optical effect (chatoyancy): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- chalcedony, including agate and jasper (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.5 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
- CIBJO definitions
- chatoyancy
Quality factors
Moss Chalcedony — quality factor (lustre): vitreous to greasy
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- chalcedony, including agate and jasper (the whole class)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.5 (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): 1.537 / 2.63; Closest values: 1Amethyst 1.548 / 2.67, 2Charoite 1.554 / 2.66, 3Changhua Stone 1.56 / 2.6, 4Shoushan Stone 1.56 / 2.7, 5Balin Stone 1.56 / 2.55
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
The CIBJO laboratory protocol covers Moss Chalcedony under “Chalcedony” (§6.1.16): see identification on the Chalcedony entry; the required tests are listed on the CIBJO laboratory protocol table for Chalcedony.
How far testing can go
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
Evidence and sources
Authority basis and clause sources
Sources
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 (Moss Chalcedony) 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)
- 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 |
| Treatments recorded for this material | Heated / Heat-treated (via parent material), Filled / Fracture-filled (via parent material), Dyed (via parent material) | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Moss Chalcedony 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.