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UnderstandWhat it is, what people ask, how far this page goes
Natural inorganic gem materials · Mineral / gemstone variety · Natural identity; treatment status unknown
Iceland Spar
A transparent, optical-grade variety of Calcite, listed as "Iceland spar" in GB/T 16552—2017 Table A.1; the name does not mean it comes from Iceland. 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 Iceland Spar 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 Iceland SparHow far lab testing can go
- Treatments and enhancements of Iceland SparThe enhancements and treatments the GB/T and JJA/AGL tables list
- Caring for and wearing Iceland SparDurability indicators and wearing advice
- Hardness, density and refractive index of Iceland SparEach value with its source and check date
- Iceland Spar in English, Chinese and Japanese; national standard namesNames in four languages, the GB/T standard name and the suggested listing name; and: Has any of GIA, FTC, CIBJO or Gem-A put a name for it on record here?
- Name origin and history of Iceland SparWhere the name comes from
- Listing and disclosing Iceland SparThe listing name to use; what must be disclosed before sale
- Standard clauses that define Iceland SparWhich 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
Iceland spar is a transparent optical variety of calcite rather than a species of its own; its parent mineral is calcite (CaCO3). As a major rock-forming mineral, calcite is present in limestones, marbles and chalks; within clastic sedimentary rocks it acts as a cement and in hydrothermal veins as gangue; igneous rocks spanning alkalic to mafic compositions also contain it, and it builds speleothems in caves; hexagonal, uniaxial negative, it disperses light very strongly. Iceland spar differs from ordinary calcite only by being highly transparent and cleavable into blocks that exhibit pronounced double refraction; in identity terms it stays within the calcite species, and CIBJO likewise groups varieties such as massive calcite and fibrous calcite under the parent species Calcite.
Scope: Applies to the identity boundary of Iceland spar as a transparent optical variety of calcite and to the genesis of calcite; Iceland spar is not treated as a separate mineral species or a separate genetic unit.
Sources Handbook of Mineralogy · CIBJO Gemstone Book 2022
Where it forms
Sedimentary/metamorphic carbonate rocks: limestones, marbles, chalks
Sources Handbook of Mineralogy
Gangue in hydrothermal veins, alkalic to mafic igneous rocks, and cave speleothems
Sources Handbook of Mineralogy
How it forms, step by step
In calcium-bearing sedimentary, metamorphic, or hydrothermal settings, calcium combines with carbonate to form calcite.
Sources Handbook of Mineralogy
Calcite crystallizes abundantly as a major rock-forming mineral in limestones, marbles, and chalks, or as gangue and speleothems.
Sources Handbook of Mineralogy
Locally it forms highly transparent, well-cleaved coarse crystal blocks, i.e. Iceland spar (the transparent optical variety).
Sources Handbook of Mineralogy
Such transparent blocks show double refraction along rhombohedral cleavage.
Sources Handbook of Mineralogy
Link to appearance
Iceland spar is colorless and transparent and cleaves along rhombohedral planes; calcite is uniaxial negative with very strong dispersion, and the strong birefringence of transparent blocks gives the pronounced double-image appearance that makes it an optical material.
Sources Handbook of Mineralogy
Timescale
The source does not state an absolute geological timescale for Iceland spar (transparent calcite) formation.
Sources Handbook of Mineralogy · CIBJO Gemstone Book 2022
Related base materials
- Calcite (CaCO3): Iceland spar is the transparent optical variety of calcite, not a separate mineral species
Supporting findings
Calcite is a major rock-forming mineral in limestones, marbles, and chalks, a cement in clastic sedimentary rocks, gangue in hydrothermal veins, and common as cave speleothems.
Evidence grade BScope: A general occurrence summary for calcite, not specific to Iceland spar.
Sources Handbook of Mineralogy
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
Asia
- Nizhnyaya Tunguska River basin, Krasnoyarsk Krai, Russia
Sources Mindat: Calcite
Europe
- Helgustaðir Mine, Reyðarfjörður, IcelandOriginal and first-reported locality of Iceland spar
Sources Mindat: Calcite · 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 is uniaxial negative with very strong dispersion, providing the optical basis for the strong birefringence and double images of its transparent variety (Iceland spar).
Evidence grade BScope: The source gives the optical class and strong dispersion but does not explicitly record the double-image phenomenon itself.
Sources Handbook of Mineralogy
Where the name comes from
The etymology provided here applies to calcite, the parent mineral, not to the variety name 'Iceland spar'. Calcite's name goes back to the Latin calx, denoting burnt lime, and points to a notable commercial application of the mineral; the source gives no etymology for 'Iceland spar'.
Evidence grade BScope: The etymology belongs to the parent mineral and does not establish the composition, locality, naturalness, or treatment of the material denoted by the trade name.
Sources Handbook of Mineralogy
Other research findings
Iceland spar's parent mineral is calcite (CaCO3), hexagonal and uniaxial negative.
Evidence grade BScope: Describes the parent calcite; Iceland spar itself is the transparent variety.
Sources Handbook of Mineralogy
Iceland spar is a transparent optical variety of calcite, not an independent mineral species; CIBJO places varieties such as fibrous calcite and massive calcite under the parent species Calcite.
Evidence grade AScope: Confirms the variety relationship; CIBJO does not list an Iceland spar name.
Sources CIBJO Gemstone Book 2022
Calcite is trimorphous with aragonite and vaterite and forms a series with rhodochrosite.
Evidence grade BScope: Describes calcite's polymorphy and series relationship.
Sources Handbook of Mineralogy
Limits of this research
- Research status: Formation, occurrence or other material-specific findings found in authoritative sources
- As a transparent variety of calcite, Iceland spar has no dedicated source among those cited; its designation and optical use are supported by the parent calcite data and by its optical character.
- The source gives calcite's optical class and strong dispersion but does not explicitly record the double-image phenomenon or a dedicated Iceland spar locality description.
- The source gives no absolute ages for calcite or Iceland spar formation.
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
- Iceland Spar
GB/T 16552—2017 Table A.1 “Iceland Spar” · IMA Mineral List 2026-07 “Calcite”
Construction or treatment status
Natural identity; treatment status unknown
Treatments recorded for this material: Dyed (via parent material), Filled / Fracture-filled (via parent material), Irradiated (via parent material)
Related:Disclosure and cautions
This page cannot answer
Natural? · Origin · Price
A lab report settles these; this wiki covers naming and disclosure.
Related:What this page can answer
Answer at a glance
Iceland Spar is Transparent optical calcite variety; use "Iceland Spar" for listings, and disclose any known treatments.
Evidence
- GB/T · Table A.1, row 冰洲石 (Iceland Spar)
What this means for you
Before buying, check the recommended listing name "Iceland Spar" 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
No care facts are recorded for this entry itself. Its parent material has care records: see Calcite.
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.
Toughness
Brittle
Daily wear
Only Mohs 3 with perfect {1011} cleavage and brittle tenacity, so it scratches easily and splits along cleavage; it is normally a display/optical material rather than daily-wear; the main risks are scratching, impact splitting and acid attack.
Care
Wipe with a barely damp soft cloth and dry immediately; avoid ultrasonic/steam cleaning and acids (a carbonate dissolves in acid, per its CaCO3 composition), and avoid soaking and sudden temperature change.
General guidance: LumaLark's general guidance inferred from the material's properties (hardness, toughness, cleavage); not text from the cited source, and not a guarantee for any specific piece.
Scope: This field describes the general physical properties of iceland spar (calcite) as a material; it makes no durability or safety promise for any specific finished product. Durability of treated (e.g. filled, dyed, coated) or assembled/composite pieces must be assessed separately for the individual item.
Treatments and identification leads
One row per treatment, with three standards side by side: how often it occurs and how stable it is (CIBJO), its category in GB/T 16552—2017 Table B.1 (this site's paraphrase) and how the JJA/AGL 2025 table lists it. Each CIBJO value links to its entry under “Testing and market”, where the wording and source are given in full.
This table scrolls sideways on narrow screens.
| Treatment | Market frequency (CIBJO) | Stability (CIBJO) | GB/T 16552 category | JJA/AGL listing | Identification leads |
|---|---|---|---|---|---|
| Dyeing | — | — | Treatment | — | — |
| Filling | — | — | Graded — see §5.4.1, Table 1 | — | — |
| Irradiation | — | — | Treatment | — | — |
“—” means the cited source gives no value for that item, not “none”. Source: GB/T 16552—2017 Table B.1 (row for Calcite)
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 GB/T 16552—2017 formal name for Iceland Spar is given in Table A.1, and the suggested listing name is Iceland Spar. Names in four languagesThe four-language names are the Simplified Chinese name, the Traditional Chinese name, the English name Iceland Spar and the Japanese name; the wording of GSJ (Japan) is not yet verified by this site, and the Japanese name shown is the entry's own. Institution usageOn authority wording, the FTC and CIBJO texts on file have no wording for this name (checked), and GIA and Gem-A are unchecked; for bodies whose text has no wording for this name, the entry's own English name is shown, which does not represent the position of FTC or CIBJO. Trade and mineralogical namesThe mineralogical name refers to a transparent, optical-grade variety of calcite.
- GSJ (Japan) formal name
- アイスランドスパー (not yet checked for this body — the entry's own Japanese name is shown)
- Chinese formal name
- 冰洲石 (GB/T 16552—2017 Table A.1)
- Mineralogical name
- Transparent optical calcite variety
Four-language names
- 简体中文
- 冰洲石
- 繁體中文
- 冰洲石
- English
- Iceland Spar
- 日本語
- アイスランドスパー
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 / gemstone variety
- Mineral chemical class
- Carbonates
- Construction or treatment status
- Natural identity; treatment status unknown
Treatments listed by standards
For Iceland Spar, this site applies the “Calcite” row of GB/T 16552—2017 Annex B, Table B.1; the standard has no separate row for Iceland Spar. As applied from the calcite row, dyeing is listed as treatment and irradiation as treatment; filling is not classed directly, its category being defined by the grades set out on the Gem treatments page. The full row including the effect column is on the Calcite page, and what Table B.1 notes is also on the Gem treatments page.
GB/T 16552-2017, Annex B, Table B.1
Under the “Calcite” row of Table B.1: Dyeing Treatment; Filling Graded — see §5.4.1, Table 1; Irradiation Treatment. The full row, with the effect column, is on the Calcite page.
What Table B.1 is, and how the “see 5.4.1” grades are defined: see the GB/T 16552: optimization vs treatment page.
What it is and how it's identified
Among the material facts for Iceland Spar, the clauses cited for structure, durability, density and optical properties are written for calcite (the whole mineral species), not measured for Iceland Spar on its own; chemical composition, fluorescence, UV-visible spectrum, infrared spectrum and magnification are likewise written for calcite (the whole mineral species) and are not repeated on the Iceland Spar entry; see the Calcite entry. Written for calcite (the whole mineral species): crystalline, trigonal, with crystals commonly tabular or prismatic; Mohs hardness 3, perfect cleavage in three directions; density 2.65–2.75 g/cm³, derived from the clause value 2.70 with tolerance ±0.05; optic character anisotropic, uniaxial, negative; refractive index 1.486–1.658; birefringence 0.172. Pleochroism when untreated is none to weak, lustre when untreated is vitreous, and among optical effects chatoyancy may be seen; pleochroism, lustre and chatoyancy are likewise written for calcite (the whole mineral species).
Registered material facts
Each row carries its own source and check date and can be cited on its own; “—” means the cited source gives no value, not “none”.
Chemical composition, luminescence, UV-visible spectrum, infrared spectrum, magnification: these whole-class features are given in the cited clause for calcite (the whole mineral species), so they are not repeated on the Iceland Spar page; see the material facts on the Calcite entry.
Items below that name the class they cover give the cited clause’s value for that whole class, not a measurement of Iceland Spar (how to read class-level values).
Structure
Iceland Spar — structure (overall): crystalline
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- calcite (the whole mineral species)
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
Iceland Spar — structure (crystal system): trigonal
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- calcite (the whole mineral species)
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
Iceland Spar — structure (crystal habit): generally platy and columnar
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- calcite (the whole mineral species)
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
Durability
Iceland Spar — Mohs hardness: 3
GB/T 16553—2017
Reference points on this site: Talc 1–3, Fluorite 4, Apatite 5–5.5, Orthoclase 6–6.5, Topaz 8, Diamond 10 (Source: GB/T 16553—2017); Gypsum 1.5–2, Calcite 3, Quartz 7 (Source: Handbook of Mineralogy); Corundum 9 (Source: GIA Gem Encyclopedia (care guide))
- Does this standard apply
- applies to this entry
- What this covers
- calcite (the whole mineral species)
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
Iceland Spar — cleavage: imperfect in three directions
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- calcite (the whole mineral species)
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
Physical properties
Iceland Spar — density: 2.65–2.75 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- calcite (the whole mineral species)
- 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
Iceland Spar — optic character: uniaxial, optically negative (anisotropic)
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- calcite (the whole mineral species)
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
Iceland Spar — refractive index: 1.486–1.658
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- calcite (the whole mineral species)
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
Iceland Spar — birefringence: 0.172
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- calcite (the whole mineral species)
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
Iceland Spar — pleochroism: none to weak
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- calcite (the whole mineral species)
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
Iceland Spar — optical effect (chatoyancy): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- calcite (the whole mineral species)
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
- CIBJO definitions
- chatoyancy
Quality factors
Iceland Spar — quality factor (lustre): vitreous
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- calcite (the whole mineral species)
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
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
The CIBJO laboratory protocol covers Iceland Spar under “Calcite” (§6.1.15): see identification on the Calcite entry; the required tests are listed on the CIBJO laboratory protocol table for Calcite.
How far testing can go
Each row's “Source & check” expands to the full source; the date beside it is the fact check date.
Clause-level definitions
Iceland Spar is registered at clause level under the entry name Iceland Spar, on the basis of GB/T 16552—2017 Annex A Table A.1, which defines it as a transparent, optical-grade variety of calcite. Cross-check result: listed directly in GB/T; not found under a standalone heading of the same name in CIBJO.
This table scrolls sideways on narrow screens.
| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Iceland Spar | GB/T 16552-2017 Annex A | Transparent optical calcite variety | Listed directly by GB/T; CIBJO carries no standalone entry under the same name. |
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 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 (Iceland Spar) is marked.
- Calcite
Sub-entries (1)
- Iceland Spar
This table scrolls sideways on narrow screens.
| Page | Content | Status |
|---|---|---|
| Browsing family | Carbonate minerals | Live |
| Treatments recorded for this material | Dyed (via parent material), Filled / Fracture-filled (via parent material), Irradiated (via parent material) | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Iceland Spar 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.