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
Microcline
A separate mineral species in the feldspar group whose green variety is Amazonite; under GB/T 16552-2017 §5.1.1 b) its mineral name can be used directly as a gem 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 Microcline forms and what gives its colourFormation setting, process and timescale, each finding graded and sourced
- How to identify MicroclineHow far lab testing can go and whether a synthetic exists
- Treatments and enhancements of MicroclineThe enhancements and treatments the GB/T and JJA/AGL tables list
- Hardness, density and refractive index of MicroclineEach value with its source and check date
- Microcline 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?
- Listing and disclosing MicroclineThe listing name to use
- Standard clauses that define MicroclineWhich 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
Microcline is the potassium feldspar species of the feldspar group; chemically it is the KAlSi3O8 end member but crystallographically triclinic, in contrast to the monoclinic orthoclase and sanidine. The alkali feldspar subgroup varies continuously between albite (NaAlSi3O8) and orthoclase (KAlSi3O8), and its varieties can only be separated by crystal structure (X-ray diffraction) rather than routine gemmology; microcline and orthoclase share a characteristic Raman peak (~450–455 cm–1) that distinguishes them from the non-potassic anorthoclase. The green variety of microcline is amazonite, one of the important feldspar gem varieties.
Scope: Covers the chemical and structural classification of microcline (triclinic potassium feldspar, KAlSi3O8) as a mineral species and the distinction of its varieties; does not address secondary structural details such as lattice exsolution or optical effects.
Sources G&G Summer 2024 · G&G Winter 2022
Where it forms
Feldspar-group minerals occur widely in many igneous and metamorphic rocks; microcline is their triclinic potassium feldspar species.
Sources G&G Summer 2024 · G&G Winter 2022
The alkali feldspar subgroup lies in the continuous albite–orthoclase solid-solution series, its composition and structure varying with formation conditions.
Sources G&G Summer 2024
How it forms, step by step
Under K-bearing magmatic or metamorphic fluid conditions, a potassium feldspar (KAlSi3O8) compound crystallizes.
A crystal whose structure ends up triclinic is microcline (versus monoclinic orthoclase/sanidine).
Final variety assignment requires X-ray diffraction to confirm the crystal structure; routine gemological properties (SG, RI, optic figure) cannot separate the alkali feldspar varieties.
When microcline carries trace colouring components it forms the green variety amazonite.
Link to appearance
Microcline itself is near-colourless to pale; its green variety (amazonite) is green to blue-green, and its variety assignment rests on structure and composition rather than appearance.
Sources G&G Summer 2024 · G&G Winter 2022
Timescale
The sources give no absolute age or duration for microcline formation.
Sources G&G Summer 2024 · G&G Winter 2022
Related base materials
- Feldspar group: Mineral group to which it belongs
- Alkali feldspar subgroup: Microcline is the triclinic potassium feldspar of the alkali feldspar subgroup
Recorded localities
Authoritative sources list the localities below; the list is not exhaustive.
North America
- Pikes Peak area, Colorado, United States
Sources Handbook of Mineralogy
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.
Other research findings
Microcline is the feldspar group's triclinic potassium species; within the alkali feldspar subgroup sit monoclinic sanidine and orthoclase alongside triclinic anorthoclase, albite and microcline.
Evidence grade AScope: Based on crystal symmetry; microcline and orthoclase share chemistry but differ in structure.
The alkali feldspar subgroup ranges between albite (NaAlSi3O8) and orthoclase (KAlSi3O8), and variety classification requires crystal structure (X-ray diffraction) rather than routine gemological properties.
Evidence grade AScope: Composition–structure classification; routine gemological properties overlap among alkali feldspars.
Microcline is the mineralogical identity of the green feldspar gem amazonite (green microcline); feldspar gem varieties include moonstone, sunstone, labradorite and amazonite.
Evidence grade AScope: Identifies amazonite as the green microcline variety; does not detail its colouring mechanism.
In Raman spectroscopy, orthoclase and microcline share a characteristic peak near 455 cm–1, which is absent in (Vietnamese) anorthoclase, aiding variety discrimination among alkali feldspars.
Evidence grade AScope: A spectroscopic criterion for these study samples; routine commercial identification still relies on structural methods.
Limits of this research
- Research status: Only partial material-specific findings found; gaps are stated as gaps
- The sources do not specifically discuss microcline’s formation temperature/pressure, occurrence or age; this record generalises from its classification within the feldspar group/alkali feldspar subgroup and its spectroscopic criterion.
- No quantitative geological data are given for microcline (or amazonite) 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
- Microcline
GB/T 16552—2017 5.1.1 b)
Construction or treatment status
Natural identity; treatment status unknown
Treatments recorded for this material: Filled / Fracture-filled (via parent material), Coated (via parent material), Diffusion-treated (via parent material), Irradiated (via parent material)
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
Microcline is Microcline feldspar; use "Microcline" 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 "Microcline" and any disclosed treatments on this page, and ask the seller for a grading report if in doubt.
- Last reviewed
- 2026-09-01
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 |
|---|---|---|---|---|---|
| Filling | — | — | Graded — see §5.4.1, Table 1 | — | — |
| Coating | — | — | Treatment | — | — |
| Diffusion | — | — | Treatment | — | — |
| Irradiation | — | — | Treatment | — | — |
“—” means the cited source gives no value for that item, not “none”. Source: GB/T 16552—2017 Table B.1 (row for Feldspar)
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
Besides Microcline, the name register records "Microcline", for which no restriction on use as a name is recorded.
Standard and listing namesThe Chinese formal name for Microcline corresponds to the “Amazonite” row of GB/T 16552—2017 Table A.1; the suggested listing name is Microcline. Trade and mineralogical namesThe mineralogical name is Microcline feldspar, and the trade name/synonym is Microcline. Names in four languagesThe four-language names cover Simplified Chinese, Traditional Chinese, English (Microcline) and Japanese; the GSJ (Japan) formal name is given in Japanese. Institution usageOn authority wording, the CIBJO Gemmological Laboratories Book 2024 has Microcline on record; the FTC text on file has no wording for this name (checked); GIA and Gem-A are unchecked. Bodies without a record show the entry's own English name, which does not represent their position.
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.
This table scrolls sideways on narrow screens.
| Name | Type | Matching | Use as a name | Basis |
|---|---|---|---|---|
| no restriction recorded (1) | ||||
| MicroclineEnglish | synonym | matched automatically | no restriction recorded | editorial ruling (no clause cited) |
How each authority words this name: see Names › Authority wording.
- GSJ (Japan) formal name
- 微斜長石
- Chinese formal name
- 微斜长石 (GB/T 16552—2017 Table A.1, row “Amazonite”)
- Mineralogical name
- Microcline feldspar
Four-language names
- 简体中文
- 微斜长石
- 繁體中文
- 微斜長石
- English
- Microcline
- 日本語
- マイクロクリン／微斜長石
See also: Misleading and prohibited trade names · Supplementary name index
Classification
- Origin
- Natural materials
- Material domain
- Natural inorganic gem materials
- Browsing family
- Feldspar materials
- Identity tier
- Mineral species
- Mineral chemical class
- Silicates
- Construction or treatment status
- Natural identity; treatment status unknown
Treatments listed by standards
GB/T Table B.1Microcline is assigned the Feldspar row of GB/T 16552—2017 Annex B, Table B.1: filling is handled by grade, and coating, diffusion and irradiation are all listed as treatments. This is this site's application of the Feldspar row of Table B.1; the standard itself registers feldspar, and Table B.1 does not register Microcline. See alsoThe notes to Table B.1 and the definitions of each filling grade are on this site's Gem treatments page, and the full Feldspar row, with the effect column, is on the Feldspar entry.
GB/T 16552-2017, Annex B, Table B.1
Under the “Feldspar” row of Table B.1: Filling Graded — see §5.4.1, Table 1; Coating Treatment; Diffusion Treatment; Irradiation Treatment. The full row, with the effect column, is on the Feldspar 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
The phase of Microcline itself is recorded as microcline (feldspar group); most other physical and optical data are taken from clauses for potassium feldspar (the whole subclass) or feldspar (the whole mineral group), not measured for Microcline on its own. Under the potassium feldspar (whole subclass) clause, the formula is KAlSi3O8, which may contain elements such as Ba, Na, Rb and Sr. Under the feldspar (whole mineral group) clause, the overall structure is crystalline, with a tabular or short prismatic habit, commonly with Carlsbad, polysynthetic and cross-hatched twinning; Mohs hardness 6–6.5, perfect cleavage in two directions; density 2.55–2.75 g/cm³, which this site notes as an overall value since the clause has finer ranges; this site gives the same note for refractive index 1.508–1.572 and birefringence 0.005–0.01; optic character anisotropic, biaxial, positive or negative. For untreated Microcline, under the feldspar (whole mineral group) clause, pleochroism is usually none and lustre vitreous; under the same clause, iridescence, chatoyancy, asterism and aventurescence may all be seen.
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 feldspar (the whole mineral group), so they are not repeated on the Microcline page; see the material facts on the Feldspar entry.
Items below that name the class they cover give the cited clause’s value for that whole class, not a measurement of Microcline (how to read class-level values).
Definition
Microcline — 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
Microcline — composition (chemistry): potassium feldspar: KAlSi3O8; may contain Ba, Na, Rb, Sr and other elements.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- potassium feldspar (the whole sub-group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 Chemical composition · Potassium feldspar (locator checked 2026-09-28)
- Fact checked on
- 2026-09-26
Microcline — composition (phase): microcline (feldspar group)
CIBJO Gemmological Laboratories Book 2024
Source & check 2026-09-22
- Source
- Fact checked on
- 2026-09-22
Structure
Microcline — structure (overall): crystalline
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Microcline — structure (crystal system): Moonstone and amazonite belong to the monoclinic or triclinic system; sunstone and labradorite are triclinic.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Microcline — structure (crystal habit): Crystals are tabular or stubby prisms; Carlsbad, polysynthetic and gridiron (cross-hatched) twinning are common.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Durability
Microcline — Mohs hardness: 6–6.5
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
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Microcline — cleavage: two directions of perfect cleavage
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Physical properties
Microcline — density: 2.55–2.75 g/cm³
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
- General note
- the clause has finer ranges
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Optical
Microcline — optic character: biaxial and anisotropic; optic sign may be either positive or negative.
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Microcline — refractive index: 1.508–1.572
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
- General note
- the clause has finer ranges
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Microcline — birefringence: 0.005–0.01
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
- General note
- the clause has finer ranges
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Microcline — pleochroism: usually absent
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Microcline — optical effect (iridescence): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Microcline — optical effect (chatoyancy): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Microcline — optical effect (asterism): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
Microcline — optical effect (aventurescence): seen
GB/T 16553—2017
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (locator checked 2026-09-26)
- Fact checked on
- 2026-09-26
- CIBJO definitions
- chatoyancy, asterism, aventurescence
Quality factors
Microcline — quality factor (lustre): vitreous
GB/T 16553—2017
- Treatment state
- untreated
- Does this standard apply
- applies to this entry
- What this covers
- feldspar (the whole mineral group)
Source & check 2026-09-26
- Source
- GB/T 16553—2017 Gems — Testing (GB/T): §5.1.17 (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): 1.54 / 2.65; Closest values: 1Charoite 1.554 / 2.66, 2Changhua Stone 1.56 / 2.6, 3Shoushan Stone 1.56 / 2.7, 4Balin Stone 1.56 / 2.55, 5Bamboo Coral 1.57 / 2.65
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 Microcline under Feldspar; for identification of Microcline see the identification part of the Feldspar entry, and the list of required tests is on the laboratory testing page. On how far testing can go, the CIBJO Gemstone Book (Blue Book) records in its Microcline row that no synthetic counterpart of Microcline is commercially available, with the registered annex code N.
The CIBJO laboratory protocol covers Microcline under “Feldspar” (§6.1.33): see identification on the Feldspar entry; the required tests are listed on the CIBJO laboratory protocol table for Feldspar.
How far testing can go
Microcline — 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
Microcline is defined directly in the list of gem materials and definitions of the CIBJO Gemmological Laboratories Book 2024, under the entry name Microcline; the definition refers to the amazonite entry and states that amazonite is the only gem variety of microcline. Cross-check result: defined directly by CIBJO; the same English name was not found directly in the GB/T annex of this edition.
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| Term | Clause | Definition | Cross-check |
|---|---|---|---|
| Microcline | 7.2.1.147 | see amazonite. Amazonite is the only gem variety of microcline | 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
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.
This table scrolls sideways on narrow screens.
| Page | Content | Status |
|---|---|---|
| Browsing family | Feldspar materials | Live |
| Treatments recorded for this material | Filled / Fracture-filled (via parent material), Coated (via parent material), Diffusion-treated (via parent material), Irradiated (via parent material) | Live |
| Related articles | To be added (placeholder) | Planned |
Who maintains this page
The material facts in the Microcline 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.