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UnderstandWhat it is, what people ask, how far this page goes
Natural inorganic gem materials · Mineral group / supergroup · Natural identity; treatment status unknown
Amphibole
A mineral group name, not a single mineral species; tremolite and actinolite are species within it and, under GB/T 16552-2017 clause 5.1.1 b), can be used directly as gem names. 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 Amphibole forms and what gives its colourFormation setting, process and timescale, each finding graded and sourced
- Caring for and wearing AmphiboleCleaning, heat, chemicals and light, as the cited sources give them; durability indicators and wearing advice
- Mohs hardness of AmphiboleEach value with its source and check date
- Amphibole in English, Chinese and Japanese; national standard namesNames in four languages, the GB/T standard name and the suggested listing name; and: Which of GIA, FTC, CIBJO and Gem-A have a name for it on record, and do those agree?
- Name origin and history of AmphiboleWhere the name comes from
- Listing and disclosing AmphiboleThe listing name to use; what must be disclosed before sale
- Standard clauses that define AmphiboleWhich 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
Amphibole is not a single mineral species but a mineral group (a higher-rank name) of many hydrous chain-silicate species. Its members are subdivided by crystal system and composition into calcic, Fe-Mn-Mg and alkali subgroups, with representative species including actinolite, tremolite, anthophyllite, gedrite and riebeckite. Their origins differ: calcic amphiboles form mainly by low-grade regional or contact metamorphism of magnesian carbonate or mafic/ultramafic rocks and also occur in glaucophane-bearing blueschists; Fe-Mn-Mg amphiboles occur in medium- to high-grade metamorphic rocks; alkali amphiboles occur in alkalic granites and syenites. Genesis must be stated for a specific species, not for the group as a whole.
Scope: Applies to an overview of the naming boundaries of the amphibole mineral group and the occurrence of its main members; specific genesis must be cited separately for each mineral species.
Sources Handbook of Mineralogy
Where it forms
Low-grade regional or contact metamorphic settings (magnesian carbonate, mafic/ultramafic rocks), and glaucophane-bearing blueschists.
Sources Handbook of Mineralogy
Rocks produced by metamorphism of medium to high grade—amphibolites, gneisses, metaquartzites, iron formations and schists among them—together with contact rocks altered by metasomatism.
Sources Handbook of Mineralogy
Alkalic granites and syenites and other alkaline igneous bodies.
Sources Handbook of Mineralogy
How it forms, step by step
Magnesian carbonate or mafic/ultramafic rocks undergo low-grade regional or contact metamorphism, forming calcic amphiboles (e.g. actinolite).
Sources Handbook of Mineralogy
Ca-Mg siliceous sediments undergo contact metamorphism, forming calcic amphiboles such as tremolite.
Sources Handbook of Mineralogy
Anthophyllite and gedrite form during medium- to high-grade metamorphism and some retrograde reactions.
Sources Handbook of Mineralogy
Alkali amphiboles (e.g. riebeckite) crystallize in alkaline igneous settings such as alkalic granites and syenites.
Sources Handbook of Mineralogy
Link to appearance
Amphibole members range from white and grey to green and black; colour relates to Fe and Mg content. As a group name, appearance cannot determine a single species.
Sources Handbook of Mineralogy
Timescale
No single age applies to the group; metamorphic ages must be measured per locality.
Sources Handbook of Mineralogy
Related base materials
- Actinolite: Representative species of the amphibole group (calcic subgroup)
- Tremolite: Representative species of the amphibole group (calcic subgroup)
- Anthophyllite: Representative species of the amphibole group (Fe-Mn-Mg subgroup)
- Gedrite: Representative species of the amphibole group (Fe-Mn-Mg subgroup)
- Riebeckite: Representative species of the amphibole group (sodic subgroup)
Supporting findings
Actinolite, a calcic member of the amphibole family, arises chiefly through low-grade metamorphism—whether regional or contact—acting on magnesian carbonate rocks and on mafic or ultramafic lithologies; glaucophane-bearing blueschists are an additional host.
Evidence grade BScope: Only for actinolite as a member; not the whole group.
Sources Handbook of Mineralogy
Tremolite (a calcic amphibole) is from contact metamorphism of Ca-Mg siliceous sediments and in greenschist-facies metamorphics derived from ultramafic or magnesium carbonate rocks.
Evidence grade BScope: Only for tremolite as a member; not the whole group.
Sources Handbook of Mineralogy
Anthophyllite and gedrite, the Fe–Mn–Mg members of the amphibole family, develop during metamorphism of medium to high grade; their hosts include amphibolites, gneisses, metaquartzites, iron formations, granulites and schists, plus rocks altered by metasomatism at contacts.
Evidence grade BScope: Only for anthophyllite/gedrite; not the whole group.
Sources Handbook of Mineralogy
Riebeckite (an alkali amphibole) occurs in alkalic granites and syenites, is rarer in felsic volcanics and granite pegmatites, and occurs in some schists and in iron formations as asbestiform crocidolite.
Evidence grade BScope: Only for riebeckite as a member; not the whole group.
Sources Handbook of Mineralogy
Where the name comes from
'Amphibole' is a group name whose etymology the cited sources do not provide; the etymologies of its representative species are these: actinolite takes its name from a Greek word for 'ray', reflecting its radiating fibrous growth; tremolite recalls the Tremola Valley in Switzerland, where it was found; anthophyllite comes from the Latin anthophyllum ('clove'), a nod to its colour; gedrite takes its name from a locality near Gèdre, France; riebeckite commemorates the German explorer Emil Riebeck (1853–1885). These etymologies pertain to those species, not to the group name amphibole.
Evidence grade BScope: The etymology explains the origin of a name only; it does not attest composition, locality, naturalness or treatment, and here belongs to the parent mineral rather than to the trade name itself.
Sources Handbook of Mineralogy
Other research findings
Amphibole is a mineral-group (higher-rank) name whose members do not all crystallize in the orthorhombic system: the orthoamphiboles (anthophyllite-gedrite series) crystallize in the orthorhombic system, whereas actinolite, tremolite and riebeckite crystallize in the monoclinic system. The amphibole group is therefore not a single mineral species.
Evidence grade BScope: Defines amphibole as a group rather than a species; limited to the naming boundary.
Sources Handbook of Mineralogy
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- Amphibole is a group name; only representative subgroup/species occurrences are overviewed and cannot be generalised.
- Member data come from Handbook of Mineralogy data sheets (level B), not peer-reviewed monographs.
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
- Amphibole group (state the specific mineral species)
GB/T 16552—2017 5.1.1 b) · CIBJO Gemmological Laboratories Book 2024 §7.2.1.13 “Amphibole”
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
"Amphibole" is a market name rather than a mineral species name; before using it, verify: Industry-wide term that does not denote a single species.
Evidence
- GB/T · 5.1.1 b)
What this means for you
Before buying, check the recommended listing name "Amphibole group (state the specific mineral species)" 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
- Amphibole group (state the specific mineral species)
Care and wear
Care
care (storage)2 sources compared
Amphibole — care (storage): A UK museum curators' paper recommends enclosing asbestiform specimens, amphibole asbestos included, in two layers of sealable polyethylene bags of food or conservation grade for routine storage.
Journal of Natural Science Collections (Horak et al., 2016)
- Treatment state
- any treatment state
Source & check 2026-10-06
- Source
- J. Horak, J. Faithfull, M. Price & P. Davidson, “Identifying and managing asbestiform minerals in geological collections”, Journal of Natural Science Collections 3: 51–61 (2016): p.58, body text (locator checked 2026-10-06)
- Fact checked on
- 2026-10-06
Amphibole — care (storage): The US National Park Service advises that asbestos minerals — all of which except chrysotile are amphiboles — may be given a second enclosure in a sealable bag; this applies only to asbestiform amphiboles.
NPS Conserve O Gram 11/11
- Treatment state
- any treatment state
Source & check 2026-10-06
- Source
- National Park Service, Conserve O Gram 11/11, “Health and Safety Issues with Geological Specimens” (September 2006): p.3, body text (locator checked 2026-10-06)
- Fact checked on
- 2026-10-06
Amphibole — care (wear): NPS warns that touching or moving an asbestos-type mineral can shed fibres that float in the air and get breathed in; this concerns the asbestiform amphiboles, not the group as a whole.
NPS Conserve O Gram 11/11
- Treatment state
- any treatment state
Source & check 2026-10-06
- Source
- National Park Service, Conserve O Gram 11/11, “Health and Safety Issues with Geological Specimens” (September 2006): p.2, 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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| Question | Matching entries |
|---|---|
| Wearing limits (knocks, settings) | NPS warns that touching or moving an asbestos-type mineral can shed fibres that float in the air and get breathed in; this concerns the asbestiform amphiboles, not the group as a whole |
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.
Mohs hardness
5–6
Toughness
Brittle, tough in fibrous aggregates
Cleavage
{110} good, intersecting at about 56° and 124°; parting on {100}
Sources Handbook of Mineralogy
VerifyNames, standards, technical facts, clauses and sources
Names
Trade and mineralogical namesAmphibole is a mineral group or supergroup name, not a single mineral species; its mineralogical name is amphibole-group minerals. Chinese standard nameUnder GB/T 16552—2017, Amphibole is not listed in Annex A and can be used directly as a gem material name. Institution usageAmong GIA, FTC, CIBJO and Gem-A, the CIBJO Gemmological Laboratories Book 2024 lists Amphibole; the FTC source text has no wording for Amphibole (checked); GIA and Gem-A have not been checked, and bodies without a recorded wording show the entry's own English name, which does not represent their position. Names in four languagesThe four-language names are given in Simplified Chinese, Traditional Chinese, English (Amphibole) and Japanese (a kanji name and a transliteration); the Japanese GSJ wording for these Japanese names is not yet verified by this site. Trade and mineralogical namesAmphibole is a trade name in general industry use but does not point to a single species. Recommended listing nameThe suggested listing name is amphibole group, with the specific mineral species stated.
- GSJ (Japan) formal name
- 角閃石／アンフィボール (not yet checked for this body — the entry's own Japanese name is shown)
- Mineral / material name (not in GB/T 16552 Annex A; usable directly)
- 角闪石 (GB/T 16552—2017 §5.1.1 b))
- Mineralogical name
- Amphibole-group minerals
Four-language names
- 简体中文
- 角闪石
- 繁體中文
- 角閃石
- English
- Amphibole
- 日本語
- 角閃石／アンフィボール
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 group / supergroup
- Mineral chemical class
- Silicates
- Construction or treatment status
- Natural identity; treatment status unknown
What it is and how it's identified
Registered material facts
Each row carries its own source and check date and can be cited on its own; “—” means the cited source gives no value, not “none”.
Definition
Amphibole — composition (phase): amphibole group
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
Clause-level definitions
Amphibole is listed in the CIBJO Gemmological Laboratories Book 2024 under the term Amphibole; the definition refers to the actinolite and nephrite entries and gives no definition of its own. The cross-check result is that it is defined directly by CIBJO, and no identically named English entry was found in this edition of the GB/T 16552—2017 annex.
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| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Amphibole | 7.2.1.13 | see actinolite, nephrite | Defined directly by CIBJO; no identically named English entry was found in this edition of the GB/T annex. |
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.
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| Page | Content | Status |
|---|---|---|
| Browsing family | Other silicate minerals | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Amphibole 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.