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UnderstandWhat it is, what people ask, how far this page goes
Natural inorganic gem materials · Rock / mineral aggregate · Natural identity; treatment status unknown
Nuummite
A metamorphic rock containing anthophyllite and gedrite that shows golden flashes on a dark groundmass; GB/T does not include this name. 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 Nuummite forms and what gives its colourFormation setting, process and timescale; where its colour and optical effects come from, each finding graded and sourced
- Caring for and wearing NuummiteCleaning, heat, chemicals and light, as the cited sources give them; durability indicators and wearing advice
- Mohs hardness of NuummiteEach value with its source and check date
- Nuummite 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 NuummiteWhere the name comes from
- Listing and disclosing NuummiteThe listing name to use; what must be disclosed before sale
- Standard clauses that define NuummiteWhich 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
Nuummite is a commercial name for the distinctly iridescent orthoamphibole found near Nuuk, Greenland, a metamorphic rock (aggregate) containing anthophyllite-gedrite amphiboles. The orthoamphibole occurs in a Precambrian sequence called the Malene supracrustals, enclosed in extensive gneisses; isotopic work shows the rocks are more than three billion years old and have undergone strong deformation and metamorphism at temperatures of at least 550 C. The orthoamphiboles form a solid-solution series between anthophyllite and gedrite; the iridescence comes from lamellae parallel to (010) less than 0.2 micron thick and is an interference effect (similar to labradorescence).
Scope: Applies to an overview of the rock properties, occurrence and genesis of nuummite (iridescent anthophyllite) from Nuuk, Greenland.
Sources G&G Spring 1987 · Handbook of Mineralogy
Where it forms
The Precambrian Malene supracrustals near Nuuk, Greenland (enclosed in extensive gneisses), which underwent strong deformation and metamorphism at temperatures of at least 550 C.
Sources G&G Spring 1987
The rock forms rusty bands/lenses composed almost exclusively of orthoamphiboles with small amounts of pyrrhotite, chalcopyrite, magnetite, molybdenite and gahnite.
Sources G&G Spring 1987
How it forms, step by step
During the Precambrian, sedimentary/volcanic material was deposited, forming the protolith of the Malene supracrustals.
Sources G&G Spring 1987
The sequence underwent strong deformation and metamorphism at temperatures of at least 550 C, forming orthoamphibole-rich layers.
Sources G&G Spring 1987
The orthoamphibole crystallized as a solid-solution series between anthophyllite and gedrite, developing very thin lamellae parallel to (010).
Sources G&G Spring 1987 · Handbook of Mineralogy
Lamellae thinner than 0.2 micron produce iridescence (interference); the best material tends to occur in high-strain areas such as fold closures.
Sources G&G Spring 1987
Link to appearance
Cut and polished nuummite shows green, golden, reddish and (rarely) violet iridescence; the effect is hard to see on rough material and becomes apparent only after cutting, and correlates with grain size.
Sources G&G Spring 1987
Timescale
Isotopic work shows the Malene supracrustals are more than three billion years old (Precambrian), metamorphosed at temperatures of at least 550 C.
Sources G&G Spring 1987
Related base materials
- Anthophyllite: Principal constituent mineral of the rock (orthoamphibole)
- Gedrite: Principal constituent mineral of the rock (orthoamphibole)
Supporting findings
Nuummite occurs in a Precambrian sequence called the Malene supracrustals, which are enclosed in extensive gneisses.
Evidence grade AScope: States its occurrence; not commercial grading.
Sources G&G Spring 1987
The Malene supracrustals underwent strong deformation and metamorphism at temperatures of at least 550 C, and the rocks are more than three billion years old.
Evidence grade AScope: Age from isotopic work; the temperature is a metamorphic lower bound.
Sources G&G Spring 1987
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
North America
- Nuuk area, GreenlandAs of 1987: several localities around Nuuk, in the Malene supracrustals
Sources G&G Spring 1987
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
Nuummite's iridescence comes from lamellae parallel to (010) less than 0.2 micron thick and is an interference effect; the iridescence is only apparent after cutting.
Evidence grade AScope: Applies to its iridescence mechanism; no artificial treatment involved.
Sources G&G Spring 1987
Where the name comes from
The cited sources give no authoritative etymology for the trade name nuummite itself. The etymologies below belong to the parent minerals: anthophyllite comes from the Latin anthophyllum ('clove'), reflecting its colour; gedrite takes its name from a locality near Gèdre, France (rendered Gµedre by an OCR error; should read Gèdre). These etymologies belong to the parent minerals, not to the trade name nuummite.
Evidence grade BScope: The etymology explains only the origin of the name; it does not establish the material's composition, locality, naturalness, or treatment.
Sources Handbook of Mineralogy
Other research findings
Nuummite is the commercial name for the distinctly iridescent orthoamphibole found near Nuuk, Greenland; orthoamphibole crystallize in the orthorhombic system.
Evidence grade AScope: Defines nuummite as a commercial name for orthoamphibole; does not claim it is a single species.
Sources G&G Spring 1987
The orthoamphiboles in nuummite form a solid-solution series between anthophyllite and gedrite, whose cell dimensions are very similar (b differs by about 1%).
Evidence grade AScope: States the anthophyllite-gedrite series relationship; end-member proportions vary by sample.
Sources G&G Spring 1987 · Handbook of Mineralogy
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- Main source is a 1987 GIA note containing OCR errors; quotes are preserved verbatim.
- Nuummite is a commercial name/rock aggregate; the genesis applies to this Greenland occurrence.
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
- Nuummite
GB/T 16552—2017 5.1.1 b) · CIBJO Gemmological Laboratories Book 2024 §7.2.1.155 “Nuummite”
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
Nuummite is Metamorphic rock containing anthophyllite and gedrite amphiboles; use "Nuummite" 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 "Nuummite" 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
Nuummite — 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
Source & check 2026-09-25
- Source
- CIBJO Blue Book — Official Gemstone Book (Coloured Stone Commission 2022) (CIBJO): §8 Annex C, Nuummite, p.34; §6.2 a (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
WearThe care and wear conclusion registered for Nuummite is that it is low in hardness and scratches easily, so wear it with care, in any treatment state. Special careThe source is the Nuummite row of the Blue Book — Official Gemstone Book of The World Jewellery Confederation (CIBJO) (Coloured Stone Commission 2022), with reference to the full table of CIBJO special care letters.
This table scrolls sideways on narrow screens.
| Question | Matching entries |
|---|---|
| Wearing limits (knocks, settings) | care (wear) |
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
5.5–6
Toughness
Brittle; fibres are elastic
Cleavage
{210} perfect, intersecting at about 54.5° and 125.5°; {010}, {100} distinct
Sources Handbook of Mineralogy
VerifyNames, standards, technical facts, clauses and sources
Names
Standard and listing namesNuummite is not listed in GB/T 16552—2017 Annex A and can be named directly as Nuummite; the suggested listing name is Nuummite. Names in four languagesThe names are given in Simplified Chinese, Traditional Chinese, English (Nuummite) and Japanese (a transliteration). Trade and mineralogical namesThe mineralogical name describes a metamorphic rock containing anthophyllite and gedrite. Institution usageAmong authority wordings, the CIBJO Gemmological Laboratories Book 2024 lists Nuummite, and this site has recorded only CIBJO's wording; the FTC source text has no wording for Nuummite (checked); GIA and Gem-A have not been checked; bodies without a recorded wording show the entry's own English name, which does not represent their position. Japanese namesThe entry's own Japanese name is a transliteration, and the Japanese GSJ wording for this name is not yet verified by this site.
- GSJ (Japan) formal name
- ヌームアイト (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)
- 努乌姆石 (GB/T 16552—2017 §5.1.1 b))
- Mineralogical name
- Metamorphic rock containing anthophyllite and gedrite amphiboles
Four-language names
- 简体中文
- 努乌姆石
- 繁體中文
- 努烏姆石
- English
- Nuummite
- 日本語
- ヌームアイト
See also: Misleading and prohibited trade names · Supplementary name index
Classification
- Origin
- Natural materials
- Material domain
- Natural inorganic gem materials
- Browsing family
- Rocks and polymineral aggregates
- Identity tier
- Rock / mineral aggregate
- Mineral chemical class
- Mixed / composition-dependent
- Construction or treatment status
- Natural identity; treatment status unknown
What it is and how it's identified
Nuummite is opaque and shows iridescence; its body colour is dark grey, brown to black, registered for the untreated state. The transparency, iridescence and body colour are registered from the cited CIBJO Gemmological Laboratories Book (2024). On body colour, this site adds that in Chapter 7 of the CIBJO Gemmological Laboratories Book, the colour descriptions for carbonado, hematite, spectrolite and other entries likewise mention grey or greyish colours, and that colour alone cannot be used to establish identity or natural origin.
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”.
Optical
Nuummite — transparency: opaque.
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Nuummite — optical effect (iridescence): iridescence.
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Nuummite — body colour: Dark grey, brown to black.
CIBJO Gemmological Laboratories Book 2024
- Treatment state
- untreated
- Qualification
In chapter 7 of the CIBJO Gemmological Laboratories Book, the colour descriptions of Carbonado, Hematite, Spectrolite and other entries also name grey or a greyish 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.
Clause-level definitions
Nuummite has a direct definition in the CIBJO Gemmological Laboratories Book 2024 under the entry Nuummite. The definition classes Nuummite as a rock, describes it as a metamorphic rock containing anthophyllite and gedrite, and notes the trade name Nuummite; the CIBJO wording is quoted in full under Clause-level definitions on this page. The cross-check result is a direct CIBJO definition, and no identically named English entry was found in the GB/T annex. The definition summary shows the rock classification and the trade name; anything further requires the original CIBJO Gemmological Laboratories Book 2024.
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| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Nuummite | 7.2.1.155 | Dark grey, brown to black, opaque, with yellow, blue and red iridescence | 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 | Rocks and polymineral aggregates | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Nuummite 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.