On this page
UnderstandWhat it is, what people ask, how far this page goes
Natural inorganic gem materials · Mineral species · Natural identity; treatment status unknown
Calcite
A calcium carbonate mineral species with the formula CaCO3. It is the main component of marble, is low in hardness and is sensitive to acid. 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.
Questions people ask about Calcite
Every sentence below is followed by the registered fact it rests on; answers add no new facts and promise no outcome.
Q1Where does calcite form?
Calcite is a major rock-forming mineral: it occurs in limestones, marbles and chalks, cements the grains of clastic sedimentary rocks, forms gangue in hydrothermal veins, occurs in alkalic to mafic igneous rocks and is common as speleothems in caves.Handbook of MineralogyIn carbonate sediments such as limestone and chalk, calcium and carbonate precipitate or lithify through diagenesis to form calcite.Handbook of MineralogyIn hydrothermal veins, igneous rocks and caves it precipitates or crystallizes as granular, stalactitic, massive or compact aggregates.Handbook of MineralogyThe source does not state a timescale or absolute age for calcite formation.Handbook of Mineralogy · CIBJO Gemstone Book 2022
Q2Is calcite too soft to wear as jewellery?
It needs care: calcite has low hardness, so it scratches easily, and it cleaves or fractures easily or is brittle, so it should be worn with care.CIBJO Gemstone Book 2022Its Mohs hardness is 3.GB/T 16553—2017Its cleavage is perfect and its tenacity brittle.Handbook of Mineralogy
Q3Which properties identify calcite, and is there synthetic calcite?
No synthetic counterpart of calcite is commercially available.CIBJO Gemstone Book 2022Its refractive index is recorded as 1.486–1.658.GB/T 16553—2017Its birefringence is recorded as 0.172.GB/T 16553—2017In the mid-infrared it shows diagnostic absorption bands from vibration of the carbonate ion.GB/T 16553—2017Whether one particular bead is natural, treated or synthetic — only a laboratory report can settle that.What this page can answer
Q4Why does calcite come in so many colours?
Its colour comes mainly from minerals included within it: pure calcite is colourless or white, while various inclusions give grey, yellow, green and many other colours.Handbook of MineralogyThe most common colours are colourless, white and pale yellow, and transparent colourless calcite is called Iceland spar.GB/T 16553—2017Under ultraviolet light calcite can fluoresce red, blue, yellow and other colours.Handbook of Mineralogy
Q5Can calcite be dyed or filled?
Yes: in dyed calcite the colour is uneven under magnification, mostly concentrated between fissures or in surface hollows, and wiping with acetone or absolute ethanol can lift the colour.GB/T 16553—2017In filled calcite the filled part has a different surface lustre with visible gas bubbles, and infrared spectra and UV fluorescence imaging show the filler and where it lies.GB/T 16553—2017Whether one particular bead is natural, treated or synthetic — only a laboratory report can settle that.What this page can answer
Q6How should you clean calcite, and what should it avoid?
Calcite is particularly susceptible to attack by acids, so keep it away from acids.CIBJO Gemstone Book 2022For satin spar calcite, CIBJO adds that it is porous and should not come into contact with coloured fluids.CIBJO Gemstone Book 2022It should not be cleaned ultrasonically.CIBJO Gemstone Book 2022Water alone barely dissolves it: a mineral-conservation database gives calcite's solubility as about 20 ppm at 25 °C, which is very slight.Mineral Sensitivity Database, Oxford (2021)
Q7What is calcite, and how is it related to aragonite?
Calcite is calcium carbonate, CaCO3; it is trimorphous with aragonite and vaterite, and forms a solid-solution series with rhodochrosite.Handbook of MineralogyIt crystallizes in the trigonal system.GB/T 16553—2017Its name traces to the Latin calx, meaning burnt lime, which points to one of its significant industrial uses.Handbook of Mineralogy
Q8Does calcite have healing powers?
There is no scientific evidence that calcite has healing powers: the UK advertising regulators ASA and CAP state that they have not seen evidence that crystal therapy can treat medical conditions.ASA/CAP guidance (UK)
Sources cited in these answers ASA/CAP guidance (UK)
What this page can answer
This page covers
- How Calcite 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 CalciteHow far lab testing can go and whether a synthetic exists
- Treatments and enhancements of Calcite2 registered treatments: status, stability, how common they are and identification leads
- Caring for and wearing CalciteCleaning, heat, chemicals and light, as the cited sources give them; durability indicators and wearing advice
- Hardness, density and refractive index of CalciteEach value with its source and check date
- Calcite in English, Chinese and Japanese; national standard namesNames in four languages, the GB/T standard name and the suggested listing name, names in national standards; 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 CalciteWhere the name comes from
- Listing and disclosing CalciteThe listing name to use; what must be disclosed before sale
- Standard clauses that define CalciteWhich 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
Calcite is the mineral calcium carbonate (CaCO3) and a major rock-forming mineral. It occurs in limestones, marbles, and chalks, is a common cement in clastic sedimentary rocks, forms gangue in hydrothermal veins, occurs in alkalic to mafic igneous rocks, and is common as speleothems in caves. Calcite is trimorphous with aragonite and vaterite and forms a series with rhodochrosite; its color often reflects included minerals.
Scope: Covers the origin, occurrence and composition of calcite as a natural calcium carbonate mineral; does not address synthetic calcium carbonate or specific trade variety names.
Sources Handbook of Mineralogy · CIBJO Gemstone Book 2022
Where it forms
Sedimentary and metamorphic rocks such as limestones, marbles, and chalks, and as cement in clastic sedimentary rocks
Sources Handbook of Mineralogy
As gangue in hydrothermal veins; in igneous rocks from alkalic through mafic; and as cave speleothems
Sources Handbook of Mineralogy
How it forms, step by step
In carbonate sediments such as limestone and chalk, calcium and carbonate precipitate or lithify through diagenesis to form calcite.
Sources Handbook of Mineralogy
In clastic sedimentary rocks, calcite precipitates as a cement that binds the grains together.
Sources Handbook of Mineralogy
It precipitates as gangue in hydrothermal veins, or crystallizes in igneous rocks and caves, forming granular, stalactitic, massive, or compact aggregates.
Sources Handbook of Mineralogy
Link to appearance
In its pure form calcite is colourless to white; trapped minerals introduce grey, yellow, green and numerous other tints. Cleavage surfaces show a pearly lustre, and the mineral can fluoresce in red, blue, yellow and other hues under ultraviolet light.
Sources Handbook of Mineralogy · CIBJO Gemstone Book 2022
Timescale
The source does not state a timescale or absolute age for calcite formation.
Sources Handbook of Mineralogy · CIBJO Gemstone Book 2022
Supporting findings
Calcite is a major rock-forming mineral: it occurs in limestones, marbles, and chalks, is a common cement in clastic sedimentary rocks, forms gangue in hydrothermal veins, occurs in alkalic to mafic igneous rocks, and is common as speleothems in caves.
Evidence grade BScope: Applies to natural calcite occurrences; excludes synthetic calcium carbonate.
Sources Handbook of Mineralogy
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
Europe
- Helgustadir mine, Reydarfjord, IcelandClassic Iceland spar locality, listed first by HoM
Sources Handbook of Mineralogy
- La Sambre quarry, Landelies, Hainaut, Belgium
Sources Mindat: Calcite
- La Florida mining area, Cantabria, Spain
Sources Mindat: Calcite
North America
- Elmwood mine, near Carthage, Tennessee, United States
Sources Mindat: Calcite
Seas and coasts
- Worldwide
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.
Causes of colour and optical effects
Calcite's color is caused mainly by included minerals within it: pure material is colorless or white, while various inclusions impart gray, yellow, green, and many other colors.
Evidence grade BScope: Refers only to color from included minerals; does not address color centers or charge-transfer mechanisms, which the source does not elaborate.
Sources Handbook of Mineralogy
Where the name comes from
Calcite's name traces to the Latin word calx, meaning "burnt lime", which points to one of its significant industrial uses.
Evidence grade BScope: This states only the origin of the name and does not establish the material's composition, locality, natural origin, or whether it was treated.
Sources Handbook of Mineralogy
Other research findings
Calcite has the formula CaCO3; it is trimorphous with aragonite and vaterite, and forms a solid-solution series with rhodochrosite.
Evidence grade BScope: Describes formula, polymorphs, and solid-solution series; does not address specific trace-element contents.
Sources Handbook of Mineralogy
Under ultraviolet light calcite can fluoresce in red, blue, yellow and further colours, and it also displays phosphorescence, cathodoluminescence and thermoluminescence.
Evidence grade BScope: Describes luminescence properties; whether and in what color a sample luminesces varies with impurities.
Sources Handbook of Mineralogy
Under the CIBJO definition, only materials formed completely by nature without human intervention qualify as 'natural'; calcite, as a natural mineral species, satisfies this identity boundary.
Evidence grade AScope: Defines its status as a natural material; does not assess locality or quality grade.
Sources CIBJO Gemstone Book 2022
A mineral-conservation database gives calcite's solubility in water as about 20 ppm at 25 °C and one atmosphere, that is, very slight.
Evidence grade BScope: A specimen-conservation reference on mineral sensitivities, not jewellery care advice; calcite's sensitivity to acids is covered by separate care facts.
Sources Mineral Sensitivity Database, Oxford (2021)
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- The source does not state a timescale or absolute age for calcite formation.
- Beyond 'included minerals,' the specific mechanisms of calcite's varied colors (e.g. color centers, charge transfer) are not elaborated in this source.
- The source lists many localities but does not quantify the specific P-T conditions of formation at each site.
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
- Calcite
GB/T 16552—2017 Table A.1 “Calcite” · CIBJO Gemmological Laboratories Book 2024 §7.2.1.37 “Calcite”
Construction or treatment status
Natural identity; treatment status unknown
Treatments recorded for this material: Dyed, Filled / Fracture-filled, Irradiated
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
Calcite is Calcite (CaCO3); use "Calcite" for listings, and disclose any known treatments.
What this means for you
Before buying, check the recommended listing name "Calcite" 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
Calcite — care (cleaning): Some stones are susceptible to damage from ultrasonic cleaning. Do not expose them to ultrasonic cleaning.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code j
- 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, Calcite, p.37; §6.2 j (locator checked 2026-09-25)
- Fact checked on
- 2026-09-25
Calcite — care (cleaning): Some stones are susceptible to damage from ultrasonic cleaning. Do not expose them to ultrasonic cleaning.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code j
- Treatment state
- any treatment state
- Applies only to
- fibrous calcite (calcite satin spar)
Source & check 2026-09-26
- Source
- Fact checked on
- 2026-09-26
Calcite — care (chemicals): Some stones are particularly susceptible to attack by acids. Keep them away from acids.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code h
- 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, Calcite, p.37; §6.2 h (locator checked 2026-09-25)
- Fact checked on
- 2026-09-25
Calcite — care (chemicals): porous, so do not let it come into contact with coloured fluids; particularly susceptible to attack by acids, so keep it away from acids.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code c, special-care code h
- Treatment state
- any treatment state
- Applies only to
- fibrous calcite (calcite satin spar)
Source & check 2026-09-26
- Source
- Fact checked on
- 2026-09-26
Calcite — care (wear): low hardness, so it scratches easily; wear with care; cleaves or fractures easily or is brittle (e.g. rubbed facet edges); wear with care.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code a, special-care code b
- 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, Calcite, p.37; §6.2 a, b (locator checked 2026-09-25)
- Fact checked on
- 2026-09-25
Calcite — care (wear): low hardness, so it scratches easily; wear with care; cleaves or fractures easily or is brittle (e.g. rubbed facet edges); wear with care.
CIBJO Gemstone Book 2022
CIBJO Gemstone Book §6.2:special-care code a, special-care code b
- Treatment state
- any treatment state
- Applies only to
- fibrous calcite (calcite satin spar)
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
CleaningCleaning Calcite: CIBJO states that it must not be cleaned ultrasonically, whatever the treatment state; CIBJO also has a conclusion specifically for fibrous calcite (Calcite Satin Spar), again for any treatment state, that it must not be cleaned ultrasonically. Chemicals: CIBJO states that Calcite is especially sensitive to acids and should be kept away from them, whatever the treatment state; CIBJO's conclusion for fibrous calcite (Calcite Satin Spar), for any treatment state, adds to that sensitivity to acids that it is porous and must not come into contact with coloured liquids. Wear: CIBJO states that Calcite is soft and scratches easily, so it should be worn with care, and fractures easily, so it should be worn with care, whatever the treatment state; CIBJO's conclusion for fibrous calcite (Calcite Satin Spar), for any treatment state, is that it is soft, scratches easily and fractures easily, so it should be worn with care.
This table scrolls sideways on narrow screens.
| Question | Matching entries |
|---|---|
| Can it go in an ultrasonic or steam cleaner? | care (cleaning); fibrous calcite (calcite satin spar): care (cleaning) |
| Contact with acids, alkalis and household chemicals | care (chemicals); fibrous calcite (calcite satin spar): porous, so do not let it come into contact with coloured fluids; particularly susceptible to attack by acids, so keep it away from acids |
| Wearing limits (knocks, settings) | low hardness, so it scratches easily; wear with care; cleaves or fractures easily or is brittle (e.g. rubbed facet edges); wear with care; fibrous calcite (calcite satin spar): low hardness, so it scratches easily; wear with care; cleaves or fractures easily or is brittle (e.g. rubbed facet edges); wear with care |
Durability and wearing
Treatments and identification leads
Registered treatmentsThe registered treatments for Calcite are filling and dyeing. Values not givenFilling has the status treated and dyeing the status colour-treated; the stability and prevalence of both are recorded as “—”, meaning the cited source gives no value, not “none”. Identification cluesIdentification leads for filling include: under magnification the filled areas differ in lustre from the host and gas bubbles may be visible; infrared spectroscopy detects characteristic bands of the filler; and luminescence imaging equipment such as a UV fluorescence viewer can show how the filler is distributed. The identification lead for dyeing is uneven colour distribution under magnification, concentrated mostly in fractures or surface pits, and the colour can be wiped off with solvents such as acetone or anhydrous ethanol. The leads for filling and dyeing are cited from GB/T 16553—2017; as registered, GB/T 16553—2017 serves only as a reference for filling and dyeing and does not govern Calcite directly. SyntheticsAccording to the registered entries, there is no synthetic Calcite on the market.
This table scrolls sideways on narrow screens.
| Treatment | Market frequency (CIBJO) | Stability (CIBJO) | GB/T 16552 category | JJA/AGL listing | Identification leads |
|---|---|---|---|---|---|
| fillingStatus: treated | — | — | Graded — see §5.4.1, Table 1 | — | See identification leads |
| dyeingStatus: colour treated | — | — | Treatment | — | See identification leads |
| Irradiation | — | — | Treatment | — | — |
Where each treatment acts (schematics): Filled / Fracture-filled · Dyed
“—” means the cited source gives no value for that item, not “none”. Source: GB/T 16553—2017; GB/T 16552—2017 Table B.1
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
Standard and listing namesThe Chinese formal name of Calcite comes from GB/T 16552—2017 Table A.1, and the suggested listing name is Calcite. Trade and mineralogical namesThe mineralogical name is Calcite (CaCO3). Names in four languagesOf the four-language names, Simplified and Traditional Chinese share the same characters, English is Calcite, and Japanese has a katakana and a kanji form, which together are also the GSJ (Japan) formal name. National standard namesAmong national and regional formal names, Germany (RAL) uses Calcit or Kalkspat and the European Union Calcite. Institution usageFor authority wording, the CIBJO Gemmological Laboratories Book 2024 records Calcite; the FTC text on file has been checked and has no wording for Calcite; GIA and Gem-A wording is unchecked. Bodies without a recorded wording show the entry's own English name, which does not represent their position.
- GSJ (Japan) formal name
- カルサイト／方解石
- Chinese formal name
- 方解石 (GB/T 16552—2017 Table A.1)
- Mineralogical name
- Calcite (CaCO3)
Four-language names
- 简体中文
- 方解石
- 繁體中文
- 方解石
- English
- Calcite
- 日本語
- カルサイト／方解石
National and regional formal names
- Germany (RAL)
- Calcit / Kalkspat
- European Union
- Calcite
See also: Misleading and prohibited trade names · Supplementary name index
Classification
- Origin
- Natural materials
- Material domain
- Natural inorganic gem materials
- Browsing family
- Carbonate minerals
- Identity tier
- Mineral species
- Mineral chemical class
- Carbonates
- Construction or treatment status
- Natural identity; treatment status unknown
Treatments listed by standards
Calcite is listed in the "Calcite" row of GB/T 16552—2017 Annex B, Table B.1 with: dyeing, which improves or changes colour, category treatment; filling, which improves or changes durability and appearance, with its category referring to the graded entries in the standard (see the Gem treatments page for the grades); and irradiation, which changes colour, category treatment. The explanation of Table B.1 and the definitions of each grade are on the Gem treatments page.
GB/T 16552-2017, Annex B, Table B.1
Table B.1, row “Calcite” (p.15):
This table scrolls sideways on narrow screens.
| Method | Effect | Category |
|---|---|---|
| Dyeing | Improves or changes colour | Treatment |
| Filling | Improves or changes durability and appearance | Graded — see §5.4.1, Table 1 |
| Irradiation | Changes colour | Treatment |
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 composition of Calcite is CaCO3, which may contain Mg, Fe, Mn and other elements, with the phase being calcite; structure crystalline, trigonal, with a habit commonly tabular or prismatic. Mohs hardness is 3, with three directions of perfect cleavage; registered as untreated, cleavage is perfect and tenacity brittle. Density is 2.65–2.75 g/cm³; the cited clause gives 2.70 with a permitted tolerance of ±0.05, and the range is derived from 2.70 and the tolerance. Optical character anisotropic, uniaxial, negative; refractive index 1.486–1.658; birefringence 0.172; transparency transparent, translucent and opaque. Untreated, pleochroism is none to weak, luminescence varies with colour or origin, and lustre is vitreous; the UV-visible spectrum is not diagnostic, and in the infrared spectrum carbonate-ion vibrations produce characteristic absorption bands in the mid-infrared region; among optical effects, the cat's-eye effect can occur; untreated, magnification shows gas-liquid inclusions, mineral inclusions, growth striations, pronounced doubling (high birefringence) and cleavage.
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
Calcite — nomenclature status: IMA status G: grandfathered (described before the IMA existed, and generally regarded as a valid species).
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Calcite — composition (chemistry): CaCO3, elements such as Mg,Fe and Mn may be contained.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.37 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Calcite — composition (phase): calcite
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Structure
Calcite — structure (overall): crystalline
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.37 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Calcite — structure (crystal system): trigonal
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.37 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Calcite — structure (crystal habit): generally platy and columnar
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.37 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Durability
Mohs hardness2 sources compared
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, Quartz 7 (Source: Handbook of Mineralogy); Corundum 9 (Source: GIA Gem Encyclopedia (care guide))
Calcite — Mohs hardness: 3
Handbook of Mineralogy
Source & check 2026-09-20
- Source
- Handbook of Mineralogy — Calcite (Mineral Data Publishing): p. 1, Physical Properties (locator checked 2026-09-20)
- Fact checked on
- 2026-09-20
Calcite — Mohs hardness: 3
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): §5.1.37 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Calcite — cleavage: imperfect in three directions
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.37 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Calcite — toughness: cleavage perfect; tenacity brittle
Handbook of Mineralogy
- Treatment state
- untreated
Source & check 2026-09-20
- Source
- Handbook of Mineralogy — Calcite (Mineral Data Publishing): p. 1, Physical Properties (locator checked 2026-09-20)
- Fact checked on
- 2026-09-20
Physical properties
Calcite — density: 2.65–2.75 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- Qualification
The clause we cite gives 2.70, with a stated tolerance of ±0.05. The range shown here is worked out from that.
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.37 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Optical
Calcite — optic character: uniaxial, optically negative (anisotropic)
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.37 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Calcite — refractive index: 1.486–1.658
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.37 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Calcite — birefringence: 0.172
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.37 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Calcite — transparency: transparent, translucent and opaque.
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Calcite — pleochroism: none to weak
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.37 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Calcite — fluorescence (overall): varies with colour or origin
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.37 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Calcite — spectrum (UV-visible): non-characteristic
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.37 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Calcite — spectrum (infrared): Diagnostic mid-IR bands come from vibration of the carbonate ion
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.37 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Calcite — optical effect (chatoyancy): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.37 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Calcite — magnification: gas-liquid inclusions, mineral inclusions, growth striations, pronounced doubling (high birefringence), cleavage.
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.37 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
body colour2 sources compared
Calcite — body colour: Colourless, white, yellow, pink, bluish, orange.
CIBJO Gemmological Laboratories Book 2024
- Treatment state
- untreated
- Qualification
In chapter 7 of the CIBJO Gemmological Laboratories Book, the colour descriptions of Gypsum, Smithsonite, Scapolite and other entries also name colourless.
- General note
- colour alone is not identity
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Calcite — body colour: occurs in many colors, most often colorless, white or pale yellow; the transparent colorless material is called Iceland Spar.
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- Qualification
GB/T 16553—2017 sums up the colour of Calcite as “all colours”; in its chapter 5, Tourmaline, Opal, Quartzite Jade and other variety clauses likewise say “all colours” or “all body colours”.
- General note
- colour alone is not identity
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.37 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
How the sources relate
- CIBJO Gemmological Laboratories Book 2024 and GB/T 16553—2017
GB/T 16553—2017 says calcite occurs in all colours, commonly colourless, white and light yellow; the CIBJO Gemmological Laboratories Book lists colourless, white, yellow, pink, bluish and orange. They agree on colourless, white and yellow.
- CIBJO definitions
- chatoyancy
Quality factors
Calcite — quality factor (lustre): vitreous
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.37 (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
This material (RI / SG midpoints): 1.572 / 2.7; Closest values: 1Shoushan Stone 1.56 / 2.7, 2Scapolite 1.558 / 2.67, 3Qingtian Stone 1.565 / 2.77, 4Aquamarine 1.58 / 2.79, 5Iolite 1.563 / 2.61
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
For filled Calcite, identification features include: under magnification the filled areas show a lustre different from the calcite itself, with gas bubbles in the filling; the infrared spectrum can detect the characteristic bands of the filler; and luminescence imaging equipment such as a UV fluorescence viewer can show where the filler is distributed. These identification leads come from GB/T 16553—2017, which serves only as a reference for filled calcite and does not govern it directly. For dyed calcite, identification features include: under magnification the colour is uneven, mostly concentrated in fractures or surface depressions; and the colour can be wiped off with solvents such as acetone or anhydrous ethanol. These identification leads come from GB/T 16553—2017, which serves only as a reference for dyed calcite and does not govern it directly. Which tests CIBJO's laboratory rules require for calcite, and what each method means, are shown in the rules table on the laboratory testing page. CIBJO's laboratory rules call for particular checks for fragility, dyeing and coating. There is no synthetic calcite on the market.
The tests the CIBJO laboratory protocol requires for this material, and what each method means, are in the protocol table on the laboratory testing page: §6.1.15.
How far testing can go
Calcite that has undergone filling can be identified by the following features: Under magnification the surface luster of the filled part differs from that of the host stone and gas bubbles are visible in the filled area; infrared spectra show characteristic absorption bands of the filler; luminescence imaging (such as a UV fluorescence viewer) shows how the filler is distributed.
GB/T 16553—2017
- Treatment state
- treated
- Does this standard apply
- can be followed as a reference only
- Treatment
- filling
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.37 (filling) (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Calcite that has undergone dyeing can be identified by the following features: Under magnification the colour is unevenly distributed and mostly concentrated between fissures or in surface hollows; wiping with acetone or absolute ethanol can lift the colour.
GB/T 16553—2017
- Treatment state
- colour treated
- Does this standard apply
- can be followed as a reference only
- Treatment
- dyeing
Source & check 2026-09-21
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.37 (dyeing) (locator checked 2026-09-21)
- Fact checked on
- 2026-09-21
Calcite — 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
Calcite — what the CIBJO laboratory protocol says to watch for: fragile, dye, coatings
CIBJO Gemmological Laboratories Book 2024
- Treatment state
- any treatment state
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.
Clause-level definitions
Calcite is defined directly in CIBJO Gemmological Laboratories Book 2024 under the term Calcite; the definition summary is the mineral species calcite, IMA status G, with the CIBJO wording quoted in full under Clause-level definitions on this page. The cross-check shows it is defined directly by CIBJO and also appears in the GB/T annex. The IMA Mineral List records it as Calcite Ca(CO3), status G, cross-checked against the RRUFF/IMA master mineral list (public domain data).
This table scrolls sideways on narrow screens.
| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Calcite | 7.2.1.37 | Colourless, white, yellow, pink, bluish, orange; transparent, translucent and opaque | Defined directly by CIBJO; also present in the GB/T annex. |
| Calcite | IMA Mineral List entry | Calcite Ca(CO3) G 1836 | Cross-checked against the RRUFF/IMA master mineral list (public domain data). |
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 Calcite 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 (Calcite) is marked.
- Calcite
Sub-entries (1)
This table scrolls sideways on narrow screens.
| Page | Content | Status |
|---|---|---|
| Browsing family | Carbonate minerals | Live |
| Treatments recorded for this material | Dyed, Filled / Fracture-filled, Irradiated | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Calcite 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.