Lazurite
Lazurite is the blue of lapis lazuli: a sodalite-group mineral redefined by the IMA in 2021, hardness 5 to 5.5, density 2.38 to 2.45, bright blue streak.
Lazurite is the blue mineral in lapis lazuli: a sodalite-group framework silicate with sulphate and a trisulphide group, Na7Ca(Al6Si6O24)(SO4)(S3)-·H2O on the September 2026 IMA list, status Rd, 2021. The Handbook gives cubic dodecahedra to 5 cm, hardness 5 to 5.5, density 2.38 to 2.45 and a bright blue streak. Lazulite is an unrelated phosphate.
In short
- The mineral, not the rock. GIA calls lapis lazuli a rock, an aggregate mainly of lazurite, calcite and pyrite, and says lazurite produces its blue. Lazurite has its own row on the September 2026 IMA-CNMNC Master List; lapis lazuli has none. The rock is covered on is lapis lazuli a mineral or a rock; this page is the mineral.
- Redefined in 2021, so two formulas. The IMA list gives Na7Ca(Al6Si6O24)(SO4)(S3)−·H2O, status Rd, 2021 s.p., country Afghanistan / Russia, with a second reference of American Mineralogist 106 (2021), 226. The 2001 Handbook lazurite sheet writes Na6Ca2Al6Si6O24[(SO4),S,Cl,(OH)]2. Both are shown because they differ.
- The sulphur ledger. Worked on standard atomic weights, the IMA formula is 11.39% sulphur by mass: 2.85% in sulphate and 8.54% in the S3 group. The sheet’s Sar-e-Sang analysis carries SO3 8.71 and S 1.84, that is 5.33% sulphur, 65.5% of it as sulphate. The analysed lazurite and the redefined ideal are not the same material on paper.
- Four framework rows with a polysulphide. Of the rows a script parses from the IMA list, four write both an Al6Si6O24-type framework and a bracketed polysulphide group: bystrite (S5), lazurite (S3), slyudyankaite (S6) and vladimirivanovite (S3 and S2).
- The lazulite gap. Lazulite, MgAl2(PO4)2(OH)2, is a phosphate the gem society says has no relation to lazurite. A 20.00 g piece reads 11.60 to 11.84 g in water as lazurite and 13.59 to 13.83 g as lazulite, more than 1.7 g apart. azurite, the mineral lazurite is named after, reads 14.70 g.
| Name | What it is | Formula (IMA) | Hardness | Density | 20.00 g piece in water | Streak | Choose this name when |
|---|---|---|---|---|---|---|---|
| Lazurite | Sodalite-group silicate with sulphate and S3 (sheet; IMA) | Na7Ca(Al6Si6O24)(SO4)(S3)−·H2O | 5–5.5 | 2.38–2.45 | 11.60–11.84 g | Bright blue | A single blue mineral, crystals or grains, blue streak |
| Lapis lazuli | A rock: mainly lazurite, calcite and pyrite (GIA) | No row | 5–6 (IGS) | 2.75 ± 0.25 (GIA) | 12.00–13.33 g | Light blue (IGS) | The blue rock, with white calcite or brassy pyrite |
| Sodalite | Sodalite-group silicate chloride (sheet) | Na4(Si3Al3)O12Cl | 5.5–6 | 2.27–2.33 | 11.19–11.42 g | White | Blue with a white streak and no pyrite |
| Haüyne | Sodalite-group silicate sulphate (sheet) | Na3Ca(Si3Al3)O12(SO4) | 5.5–6 | 2.44–2.50 | 11.80–12.00 g | Slightly bluish to colourless | Blue grains in phonolite and related rocks |
| Lazulite | Magnesium aluminium phosphate (sheet) | MgAl2(PO4)2(OH)2 | 5.5–6 | 3.122–3.240 | 13.59–13.83 g | White | Blue and heavy, white streak |
| Azurite | Copper carbonate (sheet) | Cu3(CO3)2(OH)2 | 3.5–4 | 3.773 | 14.70 g | Pale blue | Blue, soft and heavy |
What is lazurite? The IMA row and the Handbook sheet
On the list. The September 2026 IMA-CNMNC Master List gives lazurite as Na7Ca(Al6Si6O24)(SO4)(S3)−·H2O, status Rd, meaning an existing mineral redefined during the IMA era, with 2021 s.p., the year of the special procedure. The country column reads Afghanistan / Russia. The list prints the reference American Mineralogist 106 (2021), 226; this page did not fetch that paper and reports nothing from it.
On the sheet. The 2001 Handbook lazurite sheet gives Na6Ca2Al6Si6O24[(SO4),S,Cl,(OH)]2, in the sodalite group: cubic, and also monoclinic or triclinic, with triclinic and monoclinic polymorphs known; dodecahedra or, more rarely, cubes up to 5 cm, or granular, disseminated and massive. Cleavage imperfect, fracture uneven, brittle, hardness 5 to 5.5, density 2.38 to 2.45. Translucent to opaque; deep blue, azure, violet-blue or greenish blue; streak bright blue; lustre vitreous. Isotropic, anomalously anisotropic, n = 1.502 to 1.522.
The name. The sheet says lazurite is named for its color resemblance to azurite, named from the Persian lazhward, for blue. The gem society’s lapis article gives the same Persian root for lapis lazuli.
How much sulphur is in lazurite? The sulphur ledger
From the IMA formula. Na7Ca(Al6Si6O24)(SO4)(S3)−·H2O has a formula mass of 1125.64 on standard atomic weights. Its four sulphur atoms, one in the sulphate and three in the S3 group, make 11.39% of the mass: 2.85% as sulphate, 8.54% in the trisulphide. Calcium is 3.56%, sodium 14.30%, water 1.60%.
From the sheet’s analysis. The Handbook’s one analysis, from Sar-e-Sang, Afghanistan, reads SO3 8.71 and S 1.84. Converted, SO3 8.71 is 3.49% sulphur, so the total is 5.33%, and 65.5% of it is in sulphate. Its CaO 7.97 is 5.70% calcium, and the sheet recalculates it to Ca 1.65 with Mg 0.71.
The quotable line: the redefined lazurite formula holds about twice the sulphur of the analysed Sar-e-Sang lazurite on the Handbook sheet, and puts most of it in S3 rather than sulphate. Both numbers are printed; this page does not say which describes any one specimen. A label reading lazurite on old material is not wrong; the formula on it may be the older one.
Is lazurite the same as lapis lazuli?
No: lazurite is the mineral and lapis lazuli is the rock it colours. The GIA lapis lazuli page calls lapis an aggregate of several minerals, the three major ones lazurite, calcite and pyrite, with lesser diopside, amphibole, feldspar or mica, and says lazurite produces the gem’s bright royal blue. The lazurite sheet’s own association line is calcite, pyrite, diopside, humite, forsterite, haüyne and muscovite.
What is not repeated here. Why a mixture of lazurite and calcite needs pyrite or diopside to reach GIA’s density, and the count of mineral names in lapis, are worked on is lapis lazuli a mineral or a rock. How sodalite is told from lapis is on is sodalite the same as lapis lazuli, and imitations are on how to tell if lapis lazuli is real.
In the hand. The streak is the plainest difference on the sheets: bright blue for lazurite against white for sodalite and lazulite. The gem society calls streak and acid tests on lapis destructive and for a professional gemmologist only, so on a finished stone this page does not offer them; on a rough specimen, how to use a streak plate covers the method.
Lazurite, lazulite or azurite? The lazulite gap
Three blue names, three chemistries. Lazurite is a sodium calcium aluminosilicate; the Handbook lazulite sheet gives MgAl2(PO4)2(OH)2, a phosphate, hardness 5.5 to 6, density 3.122 to 3.240, white streak; the gem society’s sodalite article says lazulite has no relation to lazurite. Azurite is Cu3(CO3)2(OH)2, hardness 3.5 to 4, density 3.773, pale blue streak.
The lazulite gap: a 20.00 g blue piece reading 11.84 g or less in water is in lazurite’s range, and one reading 13.59 g or more is in lazulite’s. Worked as 20 − 20/D: lazurite 11.60 to 11.84 g, lazulite 13.59 to 13.83 g, azurite 14.70 g. The nearest figures are more than 1.7 g apart (1.76 g unrounded); the method is on how to measure specific gravity at home.
Where the gap does not help. It does not separate lazurite from sodalite, 11.19 to 11.42 g, or haüyne, 11.80 to 12.00 g, which overlap or nearly touch. For those, the streak decides. Hardness does not separate lazurite from lazulite either: 5 to 5.5 against 5.5 to 6. The method is on how to test mineral hardness properly.
Where lazurite is found: Sar-e-Sang, Baikal and Chile
The sheet’s Distribution field. Exceptional crystals from Sar-e-Sang, Badakhshan Province, Afghanistan. Well-crystallised material from the basins of the Slyudyanka and Bystraya Rivers, Sayan Mountains, near Lake Baikal, Siberia, Russia. Lyadzhuar-Darinsk, near Ishkashima, Pamir Mountains, Tajikistan. Monte Somma, Campania, and the Alban Hills, Lazio, Italy. Ontario Peak and Cascade Canyon, San Bernardino County, California, and North Italian Mountain, Gunnison County, Colorado. About 15 km north of Lake Harbour, Baffin Island, Canada. Thabapin, near Mogok, Myanmar. Along the Cazadero River, near Ovalle, Chile.
Setting. The sheet calls lazurite a contact metamorphic mineral in limestones. The gem society’s lapis article says only Afghanistan and Pakistan yield the finest lapis in commercially interesting quantities, and describes Chilean lapis as a grey and blue mixture and Colorado’s Italian Mountain lapis as stringers in limestone with much pyrite. Those are statements about the rock, not the mineral.
Under UV. The lazurite sheet records no fluorescence. The gem society’s lapis panel records orange spots or streaks under longwave in Afghan and Chilean lapis without naming the mineral that glows; see is sodalite UV reactive. The species pages are listed in the species index. We hold no catalogue and nothing here is offered for sale; the wanted list is the only commercial route.