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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
Tremolite
Also known asChrome tremolite · Hexagonite
An IMA mineral species and one of the main constituent minerals of “nephrite” in the Chinese national standard; fibrous forms raise occupational health concerns. 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 Tremolite forms and what gives its colourFormation setting, process and timescale, each finding graded and sourced
- How to identify TremoliteHow far lab testing can go and whether a synthetic exists
- Caring for and wearing TremoliteCleaning, heat, chemicals and light, as the cited sources give them; durability indicators and wearing advice
- Mohs hardness of TremoliteEach value with its source and check date
- Tremolite 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 TremoliteWhere the name comes from
- Listing and disclosing TremoliteThe listing name to use; what must be disclosed before sale
- Standard clauses that define TremoliteWhich 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
Tremolite is a calcic amphibole with the formula Ca2(Mg,Fe2+)5Si8O22(OH)2. It forms by contact metamorphism of Ca-Mg siliceous sediments, and also occurs in greenschist-facies metamorphic rocks derived from ultramafic or magnesium carbonate rocks. Critically, tremolite forms one solid-solution series with actinolite and ferro-actinolite via Fe-Mg substitution: tremolite is the magnesium-rich end (Mg/(Mg+Fe2+) >= 0.90) and actinolite the iron-rich end (Mg/(Mg+Fe2+) about 0.5-0.89). The two are therefore the Mg and Fe ends of one series, not two unrelated minerals.
Scope: Applies to the genesis, composition, solid-solution series and occurrence of tremolite as a natural calcic amphibole mineral species; does not cover synthetic materials or the gemmological naming of nephrite varieties.
Sources Handbook of Mineralogy
Where it forms
Contact metamorphic zones in Ca-Mg siliceous sediments
Sources Handbook of Mineralogy
Greenschist-facies metamorphic rocks derived from ultramafic or magnesium carbonate rocks
Sources Handbook of Mineralogy
Massive, fibrous or columnar aggregates
Sources Handbook of Mineralogy
How it forms, step by step
Ca-Mg siliceous sediments, or ultramafic/magnesium carbonate rocks, undergo contact or greenschist-facies metamorphism.
Sources Handbook of Mineralogy
Tremolite crystallizes during metamorphism as elongated prismatic or flattened bladed crystals, or as fibrous, granular or columnar aggregates.
Sources Handbook of Mineralogy
Tremolite occurs with calcite, dolomite, wollastonite, talc, diopside and related minerals.
Sources Handbook of Mineralogy
Via Fe-Mg substitution, tremolite forms a solid-solution series with actinolite and ferro-actinolite (tremolite the Mg-rich, actinolite the Fe-rich end).
Sources Handbook of Mineralogy
Link to appearance
Tremolite ranges from white and grey through lavender to pink, and appears colourless in thin section; it has a vitreous lustre. Its fibrous, tightly intergrown aggregates make up the principal constituent of nephrite jade, which displays a characteristic silky lustre and toughness.
Sources Handbook of Mineralogy
Timescale
The source states no absolute geological timescale for tremolite formation.
Sources Handbook of Mineralogy
Supporting findings
Tremolite forms by contact metamorphism of Ca-Mg siliceous sediments, and also occurs in greenschist-facies metamorphic rocks derived from ultramafic or magnesium carbonate rocks.
Evidence grade BScope: Describes tremolite's natural metamorphic origin; not laboratory synthesis.
Sources Handbook of Mineralogy
Tremolite is commonly associated with calcite, dolomite, calcian garnet, wollastonite, talc, diopside, forsterite and cummingtonite/magnesio-cummingtonite.
Evidence grade BScope: Describes tremolite'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.
Africa
- Lelatema, TanzaniaSpecimen/occurrence locality listed by the Handbook of Mineralogy; not a commercial gem source
Sources Handbook of Mineralogy
Asia
- Kozano, Badakhshan, AfghanistanSpecimen/occurrence locality listed by the Handbook of Mineralogy; not a commercial gem source
Sources Handbook of Mineralogy
Europe
- Campolungo Alp, Ticino, SwitzerlandSpecimen/occurrence locality listed by the Handbook of Mineralogy; not a commercial gem source
Sources Handbook of Mineralogy
- Bristenstock, Uri, SwitzerlandSpecimen/occurrence locality listed by the Handbook of Mineralogy; not a commercial gem source
Sources Handbook of Mineralogy
- St. Marcel, ItalySpecimen/occurrence locality listed by the Handbook of Mineralogy; not a commercial gem source
Sources Handbook of Mineralogy
- Bilin, CzechiaSpecimen/occurrence locality listed by the Handbook of Mineralogy; not a commercial gem source
Sources Handbook of Mineralogy
- Tremola Valley, St. Gotthard, SwitzerlandName derives from this occurrence (HoM Name field); not a commercial source
Sources Handbook of Mineralogy
North America
- Pierrepont, Gouverneur, Edwards and Macomb, St. Lawrence County, New York, United StatesSpecimen/occurrence locality listed by the Handbook of Mineralogy; not a commercial gem source
Sources Handbook of Mineralogy
- Franklin, Sussex County, New Jersey, United StatesSpecimen/occurrence locality listed by the Handbook of Mineralogy; not a commercial gem source
Sources Handbook of Mineralogy
- Lee, Berkshire County, Massachusetts, United StatesSpecimen/occurrence locality listed by the Handbook of Mineralogy; not a commercial gem source
Sources Handbook of Mineralogy
- Wilberforce, Ontario, CanadaSpecimen/occurrence locality listed by the Handbook of Mineralogy; not a commercial gem source
Sources Handbook of Mineralogy
South America
- Brumado area, Bahia, BrazilSpecimen/occurrence locality listed by the Handbook of Mineralogy; not a commercial gem source
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 how far testing can go on this page, the origin determination guide and the overview of recorded localities.
Where the name comes from
Tremolite is named after a find in the Tremola Valley, in the southern St. Gotthard Mountains, Switzerland; the other member of the series, actinolite, comes from a Greek word for 'ray', alluding to the radiating fibrous habit the mineral commonly shows.
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
Tremolite has the formula Ca2(Mg,Fe2+)5Si8O22(OH)2 and belongs to the calcic amphibole group.
Evidence grade BScope: Describes tremolite's composition and group; actual composition varies with solid solution.
Sources Handbook of Mineralogy
Tremolite forms one solid-solution series with actinolite and ferro-actinolite via Fe-Mg substitution; tremolite is the Mg-rich end (Mg/(Mg+Fe2+) >= 0.90) and actinolite the Fe-rich end (about 0.5-0.89), so the two are not unrelated minerals.
Evidence grade BScope: Defines the tremolite-actinolite solid-solution relation; the actual Mg/Fe ratio requires measured composition.
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 tremolite formation.
- The specific Mg/Fe ratio distinguishing tremolite from actinolite requires measured composition.
- This record describes the tremolite mineral species only; it does not cover nephrite jade nomenclature or grading.
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
- Tremolite
GB/T 16552—2017 5.1.1 b) · IMA Mineral List 2026-07 “Tremolite”
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
Tremolite is Tremolite (IMA mineral species); use "Tremolite" for listings, and disclose any known treatments.
Evidence
- GB/T · 5.1.1 b)
What this means for you
Before buying, check the recommended listing name "Tremolite" 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
Tremolite — care (chemicals): dissolves on contact with solvents such as nail varnish remover; keep it away from all solvents and other strong chemicals.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code i
- Treatment state
- any treatment state
- Applies only to
- hexagonite and chrome tremolite
Source & check 2026-09-26
- Source
- Fact checked on
- 2026-09-26
Tremolite — care (wear): Some stones are prone to scratching due to low hardness. Wear them with care.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code a
- Treatment state
- any treatment state
- Applies only to
- hexagonite and chrome tremolite
Source & check 2026-09-26
- Source
- 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.
Common care questions and matching entries
The care entry for Tremolite in the CIBJO Official Gemstone Book (2022) states: it dissolves on contact with solvents such as nail-polish remover, so keep it away from all solvents and other harsh chemicals; it is soft and scratches easily, so wear it with care. The treatment status is regardless of treatment status, and the entry applies only to hexagonite and chrome tremolite.
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| Question | Matching entries |
|---|---|
| Contact with acids, alkalis and household chemicals | hexagonite and chrome tremolite: dissolves on contact with solvents such as nail varnish remover; keep it away from all solvents and other strong chemicals |
| Wearing limits (knocks, settings) | hexagonite and chrome tremolite: care (wear) |
Durability and wearing
Mohs hardness
5–6
VerifyNames, standards, technical facts, clauses and sources
Names
Besides Tremolite, the name register records "Chrome tremolite" and "Hexagonite", for which no restriction on use as a name is recorded (CIBJO Gemmological Laboratories Book 2024 §7.2.1.55 “Chrome tremolite”; CIBJO Gemmological Laboratories Book 2024 §7.2.1.108 “Hexagonite”).
Standard and listing namesThe Chinese formal name for Tremolite is based on the “Nephrite” row of GB/T 16552—2017 Table A.2; the mineralogical name is Tremolite, an IMA mineral species; the suggested listing name is Tremolite. Names in four languagesThe four-language names cover Simplified Chinese, Traditional Chinese, English (Tremolite) and Japanese; the GSJ (Japan) formal name is given in Japanese. Institution usageOn authority wording, CIBJO has Tremolite on record (CIBJO Gemmological Laboratories Book 2024), the FTC text on file has no wording for Tremolite (checked), and GIA and Gem-A are unchecked; bodies without a record show Tremolite, which does not represent their position. Chrome tremolite and Hexagonite are also registered for Tremolite as narrower names (variety/subtype), with no restriction recorded on their use as names.
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.
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| Name | Type | Matching | Use as a name | Basis |
|---|---|---|---|---|
| no restriction recorded (2) | ||||
| Chrome tremoliteEnglish | narrower name (variety or subtype) | matched automatically | no restriction recorded | CIBJO Gemmological Laboratories Book 2024 §7.2.1.55 “Chrome tremolite” |
| HexagoniteEnglish | narrower name (variety or subtype) | matched automatically | no restriction recorded | CIBJO Gemmological Laboratories Book 2024 §7.2.1.108 “Hexagonite” |
How each authority words this name: see Names › Authority wording.
- GSJ (Japan) formal name
- 透閃石
- Chinese formal name
- 透闪石 (GB/T 16552—2017 Table A.2, row “Nephrite”)
- Mineralogical name
- Tremolite (IMA mineral species)
- Trade names and synonyms
- Chrome tremolite (narrower name (variety or subtype)) · Hexagonite (narrower name (variety or subtype))
Four-language names
- 简体中文
- 透闪石
- 繁體中文
- 透閃石
- English
- Tremolite
- 日本語
- トレモライト／透閃石
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
What it is and how it's identified
Registered material facts for Tremolite: its naming status is IMA status Rd, a redefined existing mineral species; its composition (phase) is tremolite; cleavage is perfect in two directions; transparency is transparent or translucent; and body colour in the untreated state is greyish brown, green, colourless, white or pink. This site notes that in Chapter 7 of the CIBJO Gemmological Laboratories Book, entries such as diaspore, enstatite and albite also include brown or brownish tones in their colour descriptions.
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
Tremolite — nomenclature status: IMA status Rd: redefined (a mineral already known, given a new definition in the IMA era).
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Tremolite — composition (phase): tremolite
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Durability
Tremolite — cleavage: two directions of perfect cleavage
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.2.2 Cleavage · Tremolite (locator checked 2026-09-28)
- Fact checked on
- 2026-09-26
Optical
Tremolite — transparency: transparent, translucent.
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Tremolite — body colour: Grey-brown, green, colourless, white, pink.
CIBJO Gemmological Laboratories Book 2024
- Treatment state
- untreated
- Qualification
In chapter 7 of the CIBJO Gemmological Laboratories Book, the colour descriptions of Diaspore, Enstatite, Albite and other entries also name brown or a brownish colour.
- General note
- colour alone is not identity
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.
Testing and market
The testing and market finding registered for Tremolite is that there is no synthetic Tremolite on the market, and this finding applies to any treatment state; it is cited from the CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022).
How far testing can go
Tremolite — synthetic counterpart on the market: No synthetic counterpart of this material is commercially available
CIBJO Gemstone Book 2022
- Treatment state
- any treatment state
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
Clause-level definitions for Tremolite in the CIBJO Gemmological Laboratories Book 2024: Chrome tremolite is defined as a green, transparent or translucent chromium-bearing variety of tremolite; Hexagonite as a pink to purple, transparent variety of tremolite; and the definition of Tremolite states that the mineral species is tremolite, with IMA status Rd, the CIBJO wording being quoted in full under Clause-level definitions on this page. For Chrome tremolite, Hexagonite and Tremolite the cross-check result is defined directly by CIBJO, and the same English name was not found directly in the GB/T annex of this edition. The entry for Tremolite in the IMA list of minerals is registered as Tremolite ☐Ca2(Mg5.0-4.5Fe2+0.0-0.5)Si8O22(OH)2 Rd 2012 s.p., cross-checked against the RRUFF/IMA list of minerals main table (public-domain data).
This table scrolls sideways on narrow screens.
| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Chrome tremolite | 7.2.1.55 | Green, transparent or translucent, chromian variety of tremolite | Defined directly by CIBJO; no identically named English entry was found in this edition of the GB/T annex. |
| Hexagonite | 7.2.1.108 | Pink to purple, transparent variety of tremolite | Defined directly by CIBJO; no identically named English entry was found in this edition of the GB/T annex. |
| Tremolite | 7.2.1.246 | Grey-brown, green, colourless, white, pink; transparent, translucent | Defined directly by CIBJO; no identically named English entry was found in this edition of the GB/T annex. |
| Tremolite | IMA Mineral List entry | Tremolite ☐Ca2(Mg5.0-4.5Fe2+0.0-0.5)Si8O22(OH)2 Rd 2012 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 Tremolite on this site: 6 entries listed by this site's parent-entry links; synthetic, treated and similar entries carry their recorded state after the name; this page (Tremolite) is marked.
- Tremolite
Sub-entries (2)
- Hetian Yu / Nephrite
- Nephrite
Sub-entries (1)
This table scrolls sideways on narrow screens.
| 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 Tremolite 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.