Jadeite
Jadeite is the sodium aluminium pyroxene NaAlSi2O6: monoclinic, hardness 6 to 7, density 3.24 to 3.43, cleavages near 87 degrees. One of the two jade minerals.
Jadeite is a sodium aluminium pyroxene, NaAlSi2O6 on the IMA list: monoclinic, hardness 6 to 7, density 3.24 to 3.43, with two cleavages meeting at about 87°. It is one of the minerals the word jade covers: GIA names jadeite, nephrite and, under certain conditions, green omphacite. Crystals are rare; nearly all jadeite is massive.
In short
- A species, inside a rock name. The September 2026 IMA-CNMNC Master List lists jadeite as NaAlSi2O6, status A, 1988 s.p., country Myanmar, first reference to the Comptes Rendus of 1863. The Handbook of Mineralogy sheet writes Na(Al,Fe3+)Si2O6, Pyroxene group. By script the list has no row for jade or nephrite; the naming question is on is jade a mineral.
- The four-cation check. A pyroxene of this formula holds 4 cations per 6 oxygens. Recalculated from the sheet’s printed oxides, the New Idria, California analysis closes at 4.00, with silicon 2.00 and sodium 98.7% of its site: near end-member jadeite. The Cloverdale analysis closes at only 3.89, silicon 2.08, as the sheet’s own formula line also shows.
- The 87-degree rule. The jadeite, omphacite and aegirine sheets give {110} cleavages meeting at about 87°; the actinolite and tremolite sheets, the amphiboles of nephrite, give 56° and 124°. On a crystal or a cleavage fragment that angle separates the two jade minerals. On massive jade the cleavage cannot be seen.
- Heavier than nephrite, but the sheets touch. A 20.00 g piece reads 13.83 to 14.17 g in water as jadeite and 13.40 to 13.83 g as actinolite; the two density ranges meet at 3.24. Vesuvianite, sold as “American jade”, reads 13.98 to 14.17 g, inside jadeite. The home sequence is on how to tell if jade is real.
- Localities on the sheet: around Tawmaw, Kachin State, northern Myanmar; the Ohmi area, Niigata, and Shibukawa, Japan; around Lake Baikal, Russia; Cloverdale, Clear Creek near New Idria, and Mendocino County, California; and Manzanal in the Motagua Valley, Guatemala. It names no British locality.
| Mineral (IMA formula) | Chain type; jade role | Cleavage angle on the sheet | Hardness | Density, measured | Refractive indices (sheet) | 20.00 g piece in water |
|---|---|---|---|---|---|---|
| Jadeite, NaAlSi2O6 | Pyroxene; jadeite jade | {110} at about 87° | 6 to 7 | 3.24 to 3.43 | α 1.640 to 1.681; γ 1.652 to 1.692 | 13.83 to 14.17 g |
| Omphacite, (Ca,Na)(Mg,Fe,Al)Si2O6 | Pyroxene, 25 to 75% jadeite (sheet); green omphacite counts as jade under certain conditions (GIA) | {110} at about 87° | 5 to 6 | 3.16 to 3.43 | α 1.662 to 1.701; γ 1.685 to 1.723 | 13.67 to 14.17 g |
| Aegirine, NaFe3+Si2O6 | Pyroxene; ferric iron where jadeite has aluminium | {110} at about 87° | 6 | 3.50 to 3.60 | α 1.722 to 1.776; γ 1.795 to 1.836 | 14.29 to 14.44 g |
| Actinolite, ☐Ca2(Mg4.5-2.5Fe2+0.5-2.5)Si8O22(OH)2 | Amphibole; the sheet’s tenacity line names nephrite jade | {110} at 56° and 124° | 5 to 6 | 3.03 to 3.24 | α 1.613 to 1.646; γ 1.636 to 1.666 | 13.40 to 13.83 g |
| Tremolite, ☐Ca2(Mg5.0-4.5Fe2+0.0-0.5)Si8O22(OH)2 | Amphibole; series with actinolite | {110} at 56° and 124°, perfect | 5 to 6 | 2.99 to 3.03 | α 1.605 to 1.613; γ 1.630 to 1.636 | 13.31 to 13.40 g |
| Vesuvianite, (Ca,Na)19(Al,Mg,Fe)13(SiO4)10(Si2O7)4(OH,F,O)10 | Not a chain silicate; sold as “American jade” (IGS) | {110} poor | 6 to 7 | 3.32 to 3.43 | ω 1.703 to 1.752; ε 1.700 to 1.746 | 13.98 to 14.17 g |
What is jadeite? The pyroxene in jadeite jade
The names. The September 2026 IMA-CNMNC Master List gives jadeite the formula NaAlSi2O6, status A with the year 1988 s.p. (a special procedure under the IMA), the country Myanmar, and a first reference to the Comptes Rendus de l’Académie des Sciences, volume 56 (1863), page 861. The Handbook sheet writes Na(Al,Fe3+)Si2O6 and the group line Pyroxene group. Its Name field: from jade, a material commonly containing jadeite, in turn from the Spanish piedra de yjada, colic stone. The International Gem Society says the French mineralogist Alexis Damour distinguished jade as two minerals, jadeite and nephrite, in 1863; Hobbs, “The Jade Enigma”, Gems & Gemology, Spring 1982 adds that Damour placed nephrite with tremolite and actinolite in 1846.
What it looks like, per the sheet. Monoclinic; crystals rare, prismatic with {110}, {111} and {100} dominant, showing cleavage faces to 1 cm; commonly massive, fibrous, granular or compact, and very tough when massive. Apple-green, emerald-green, bluish green, leek-green, greenish white or white, sometimes with green spots, rarely blue or violet. White streak; subvitreous lustre, pearly on cleavages.
Jadeite the mineral, jade the rock. GIA writes that jadeite and nephrite are actually metamorphic rocks made up of tiny interlocking mineral crystals. Hobbs notes that jadeite may be an intimate intergrowth with the related pyroxenes acmite or diopside, and that the blackish green, iron-bearing material called chloromelanite has a slightly higher index and density. A script finds no IMA row for chloromelanite. Jadeite the species is the crystal; jadeite jade is a rock made mostly of it.
Is my jade pure jadeite? The four-cation check, worked
The rule, as arithmetic. NaAlSi2O6 has four cations for every six oxygens: one sodium, one aluminium, two silicon. Recalculate an analysis on six oxygens and the total should come to 4.00, with silicon at 2.00. Pure jadeite is 11.37% sodium, 13.35% aluminium and 27.79% silicon by mass on standard atomic weights.
New Idria, California. The sheet’s first analysis reads SiO2 59.06, Al2O3 24.62, Na2O 14.95, with small Fe2O3, FeO, MgO, CaO, TiO2 and MnO and 0.10 of water, total 99.96. On six oxygens: silicon 2.00, aluminium 0.98, sodium 0.98, calcium 0.01, iron and magnesium 0.02 together; 4.00 cations. Sodium is 98.7% of the large-cation site and aluminium 97.3% of the small one. The sheet’s printed line, (Na0.98Ca0.01)(Al0.98Fe3+0.01Mg0.01)Si2.00O6, agrees.
Cloverdale, California. The second analysis reads SiO2 61.66, Al2O3 21.81, Na2O 12.27, CaO 1.38, MgO 0.98, K2O 0.57, total 99.87. On six oxygens it gives silicon 2.08, a large-cation site of 0.88 and a small-cation site of 0.93: 3.89 cations, short of 4. The sheet prints the same shortfall, sums of 0.87 and 0.94 with Si2.08. The sheet does not say why, and we do not guess. The check shows only that a massive sample called jadeite need not analyse as a clean pyroxene; the specific-gravity method is on how to measure specific gravity at home.
Jadeite or nephrite on a crystal: the 87-degree rule
The 87-degree rule: two cleavages meeting near 87° mean a pyroxene, such as jadeite; near 56° and 124°, an amphibole, such as the actinolite of nephrite. The jadeite sheet prints good {110} cleavage with (110) to (1-10) at about 87°, and the omphacite and aegirine sheets print the same angle. The actinolite sheet prints good {110} cleavage intersecting at 56° and 124°, and the tremolite sheet perfect {110} at the same angles.
Where it works and where it does not. The rule needs a crystal, or a cleavage fragment with two faces you can see; jadeite crystals are rare, and nephrite is an interwoven fibrous aggregate. On a carving or a cabochon the cleavages are invisible, and the separation moves to refractive index and density. GIA gives jadeite 1.666 to 1.680 and specific gravity 3.34, nephrite 1.606 to 1.632 and 2.95. Hobbs gives spot readings of about 1.66 for jadeite and 1.61 to 1.62 for nephrite.
The documented overlap. On the sheets, jadeite’s measured density runs 3.24 to 3.43 and actinolite’s 3.03 to 3.24: the ranges meet at 3.24, which is 13.83 g in water for a 20.00 g piece. Jadeite’s lowest index, α 1.640, is below actinolite’s highest, γ 1.666. An iron-rich nephrite and an impure jadeite can therefore read alike. The step-by-step home sequence is on how to tell if jade is real.
Imperial jade, A jade and B jade: what GIA says
Imperial jade is a quality name, not a species. GIA writes that the finest jadeite, almost transparent with a vibrant emerald-green color, is known as imperial jade. The IMA list has no row for it, by script. GIA also writes that Fei Cui is a traditional Chinese term for jadeite jade, now used in parts of Asia for jadeite, kosmochlor and omphacite.
A, B and C jade. GIA’s jade buyer’s guide describes a classification used in China: A jade is jadeite that is natural or polished with wax only; B jade is jadeite bleached with acid and then impregnated with polymer resin; C jade is dyed. GIA’s gem treatment page says bleaching leaves jadeite slightly porous or prone to breakage along fractures, which is why it is followed by polymer impregnation. Fritsch and co-authors, in Gems & Gemology in 1992, found infrared spectroscopy the only method that conclusively proved polymer impregnation in all cases.
Synthetic jadeite. The International Gem Society says General Electric synthesised jadeite in the 1980s and imperial-quality green material in 2002, and has not released it commercially. This page gives no buying advice. We hold no catalogue and nothing here is offered for sale; the wanted list is the only commercial route.
Where jadeite is found: Myanmar, Japan, California and Guatemala
The Occurrence field: in high-pressure metamorphic rocks of the glaucophane facies, and as a component of eclogite. Its associates are albite, quartz, muscovite, omphacite, glaucophane, calcite, aragonite, analcime and zeolites.
The Distribution field opens in small amounts at many places; the origin of many specimens is obscure, and names: around Tawmaw, Myitkyina-Mogaung district, Kachin State, northern Myanmar; the Ohmi area along the Hashidate and Kotake Rivers, Niigata Prefecture, and Shibukawa, Gumma Prefecture, Japan; around Lake Baikal, Siberia, Russia; in California, crystals in boulders along the Russian River near Cloverdale, at Clear Creek near New Idria, San Benito County, and several places in Mendocino County; and Manzanal in the Motagua Valley, Guatemala.
In Britain the sheet names nothing, and we add nothing. A note on labels: the sheet’s own warning that many specimens’ origin is obscure is a reason to keep a locality only where it is documented. The related phosphate that the International Gem Society says can resemble translucent jadeite when cut, metavariscite, is on variscite. The reference section is at the species index, and the wanted list explains what we look for.