Is lazulite the same as lapis lazuli?
No. Lazulite is a phosphate mineral, MgAl2(PO4)2(OH)2, hardness 5.5 to 6; lapis lazuli is a rock of lazurite, calcite and pyrite. One reading or two decides.
No. Lazulite is a magnesium aluminium phosphate, MgAl2(PO4)2(OH)2 on the IMA list, one monoclinic mineral with hardness 5.5 to 6 and a white streak. Lapis lazuli is a rock, mainly lazurite, calcite and pyrite (GIA). On a refractometer lazulite gives two readings 0.031 or more apart near 1.60 to 1.66; lapis gives one, about 1.500.
In short
- One mineral against one rock. The Handbook of Mineralogy lazulite sheet describes a single monoclinic phosphate, MgAl2(PO4)2(OH)2, in dipyramidal crystals to 15 cm, forming a series with scorzalite, the iron member. The GIA lapis lazuli page calls lapis lazuli a rock, an aggregate of several minerals, mainly lazurite, calcite and pyrite. The International Gem Society lazulite article says lazulite has no relation to lapis lazuli.
- The one-reading-or-two rule. Lazulite is biaxial: its sheet prints α 1.604 to 1.626 and γ 1.637 to 1.663, and IGS gives a birefringence of 0.031 to 0.036. Lapis gives one reading, 1.500 on GIA’s figures, and its blue mineral, lazurite, is isotropic at 1.502 to 1.522. Two readings 0.03 apart above 1.60 is lazulite territory; one near 1.50 is lapis or sodalite.
- The phosphorus ledger. Worked from the IMA formulas on standard atomic weights, lazulite is 46.97% P2O5 and contains neither sulphur nor silicon. Lazurite contains no phosphorus and is 11.39% sulphur; sodalite carries 7.32% chlorine; azurite is a carbonate, 55.31% copper. A laboratory reads the answer in the anion, not the colour.
- Documented failure: GIA’s 1.670. GIA says lapis sometimes reads 1.670. That lone reading sits 0.007 above lazulite’s highest printed γ and inside scorzalite’s γ range, 1.663 to 1.680. One reading at 1.67 is not evidence of lazulite; the second reading, or its absence, is.
- The names cause the confusion. The Handbook derives lazulite from the German lazurstein, blue stone, and both lazurite and azurite from the Persian lazhward, blue. A script finds no IMA line containing the word lazuli: lapis lazuli is a rock name. How lapis is told from sodalite is on is sodalite the same as lapis lazuli, and its rock status on is lapis lazuli a mineral or a rock.
| Class | Formula (IMA) | System | Hardness | Density / SG | Streak | Optical class | Indices | Refractometer readings | Pleochroism | |
|---|---|---|---|---|---|---|---|---|---|---|
| Lazulite | Phosphate | MgAl2(PO4)2(OH)2 (A, 1967 s.p.) | Monoclinic | 5.5 to 6 | 3.122 to 3.240 | White | Biaxial (−) | α 1.604–1.626, β 1.626–1.654, γ 1.637–1.663; birefringence 0.031–0.036 (IGS) | Two | Strong: colourless, blue, darker blue |
| Scorzalite | Phosphate | Fe2+Al2(PO4)2(OH)2 (G, 1949) | Monoclinic | 6 | 3.33 | White to pale blue | Biaxial (−) | α 1.626–1.645, γ 1.663–1.680 | Two | Colourless; blue; blue |
| Lapis lazuli (rock) | Rock: mainly lazurite, calcite, pyrite (GIA) | No IMA row | Aggregate | 5 to 6 (IGS) | 2.75 ± 0.25 (GIA) | Light blue (IGS) | - | 1.500, sometimes 1.670 (GIA) | One | - |
| Lazurite | Silicate (sodalite group) | Na7Ca(Al6Si6O24)(SO4)(S3)−·H2O (Rd, 2021 s.p.) | Cubic | 5 to 5.5 | 2.38 to 2.45 | Bright blue | Isotropic; anomalously anisotropic | n 1.502–1.522 | One | None printed |
| Sodalite | Silicate (sodalite group) | Na4(Si3Al3)O12Cl (G, 1811) | Cubic | 5.5 to 6 | 2.27 to 2.33 | White | Isotropic | n 1.483–1.487 | One | None printed |
| Azurite | Carbonate | Cu3(CO3)2(OH)2 (G, 1824) | Monoclinic | 3.5 to 4 | 3.773 | Pale blue | Biaxial (+) | α 1.730, γ 1.835–1.838 | Two, 0.105 to 0.108 apart | In shades of blue |
Why do lazulite and lapis lazuli sound the same?
Three blue minerals have names built on the same idea, and none of them is lapis lazuli. The Handbook of Mineralogy lazulite sheet derives lazulite from the German lazurstein, for blue stone. The lazurite sheet names lazurite for its colour resemblance to azurite, from the Persian lazhward, for blue; the azurite sheet derives azurite from the same Persian word. Lapis lazuli is the rock in which lazurite supplies the blue.
What the IMA list records. A script over the September 2026 list finds rows for lazulite, MgAl2(PO4)2(OH)2, status A, 1967 s.p., Austria; scorzalite, Fe2+Al2(PO4)2(OH)2, G, 1949, Brazil; lazurite, Na7Ca(Al6Si6O24)(SO4)(S3)−·H2O, Rd, 2021 s.p.; sodalite; and azurite. A whole-word search finds no line containing lazuli. Four lines contain Lapis, and each is the German mineral magazine of that name cited as a reference. Lazurite’s own page, with its sulphur ledger, is lazurite.
Lazulite and scorzalite are one series. The lazulite sheet says it forms a series with scorzalite, and IGS calls them the lazulite group, magnesium and iron members, with the same colours and strong pleochroism but specific gravity and optics that vary with the Fe/Mg ratio. A blue phosphate between the two needs an analysis to be named.
How do you tell lazulite from lapis lazuli? The one-reading-or-two rule
On a refractometer, lazulite shows two shadow edges and lapis lazuli one. Lazulite is biaxial (−) on its sheet, α 1.604 to 1.626, β 1.626 to 1.654, γ 1.637 to 1.663; the International Gem Society lazulite article gives its birefringence as 0.031 to 0.036. GIA gives lapis a single index, 1.500, and no birefringence. Lazurite is isotropic, n 1.502 to 1.522, and sodalite isotropic at 1.483 to 1.487. Lazulite’s lowest index sits 0.104 above GIA’s lapis reading and 0.082 above lazurite’s highest.
Pleochroism says the same thing without an instrument. The lazulite sheet prints strong pleochroism, X colourless, Y blue, Z darker blue: a transparent crystal changes from colourless to deep blue as it is turned. Lazurite and sodalite are isotropic and print none. Lapis, an opaque rock, shows none to the eye.
Streak, with a caveat. The lazulite sheet gives a white streak; IGS says natural lapis should leave a light blue streak, and the lazurite sheet gives bright blue. Sodalite’s streak is white too, so a white streak rules out lapis but does not name lazulite. Technique is on how to use a streak plate; IGS warns that streak testing is destructive and not for finished gems.
What makes lazulite a phosphate? The phosphorus ledger
Lazulite is 46.97% P2O5 by mass and contains no silicon or sulphur; lapis lazuli’s blue mineral contains no phosphorus. Worked from the IMA formulas on standard atomic weights: lazulite, MgAl2(PO4)2(OH)2, formula mass 302.22, is MgO 13.34%, Al2O3 33.74%, P2O5 46.97% and H2O 5.96%, with 20.50% phosphorus. The scorzalite end-member, FeAl2(PO4)2(OH)2, is 42.53% P2O5. Lazurite is 11.39% sulphur, the figure on the lazurite page, and 14.97% silicon; sodalite 7.32% chlorine; azurite 55.31% copper and 25.54% CO2.
Against the sheet’s analysis. The lazulite sheet prints a Graves Mountain, Georgia, analysis of P2O5 45.79, Al2O3 32.49, MgO 10.38 and FeO 3.95, close to the magnesium end-member with some iron, as the series with scorzalite allows. Lapis, a mixture, has no single analysis; GIA lists lesser diopside, amphibole, feldspar or mica beside the three main minerals. What makes lapis outweigh pure lazurite is worked on is lapis lazuli a mineral or a rock and not repeated here.
Where the rule fails: GIA’s 1.670 and azurite’s two readings
GIA says lapis sometimes reads 1.670, and that single figure lies 0.007 above lazulite’s highest printed γ and inside scorzalite’s γ range of 1.663 to 1.680. A lone reading at 1.67 is therefore not lazulite evidence: the rule needs the second edge, 0.031 or more lower. GIA does not say which mineral in lapis gives 1.670, and this page does not guess.
Azurite also gives two readings, and is blue. Its sheet prints α 1.730 and γ 1.835 to 1.838, a gap of 0.105 to 0.108, three times lazulite’s, with a pale blue streak and hardness 3.5 to 4 against lazulite’s 5.5 to 6. IGS lists azurite, blue apatite, turquoise, blue tourmaline, topaz and lapis lazuli among the stones lazulite is mistaken for. Weights for lazulite against lazurite and azurite are already on the lazurite page (13.59 to 13.83 g against 11.60 to 11.84 g and 14.70 g in water for 20.00 g) and agree with this page’s densities.
Where lazulite is found
The lazulite sheet’s Distribution field gives many minor localities, with well-crystallised or rich material from Färbergraben and Höllgraben near Werfen, Salzburg, Austria; very large crystals from Hålsjöberg, Värmland, Sweden; large crystals from Graves Mountain, Georgia; the Champion mine and Vulcanus claim, Mono Co., California; fine crystals from Cross-cut Creek in the Big Fish River–Rapid Creek area, Yukon; Dattas, Minas Gerais, Brazil; Mt. Bity, Madagascar; and fine gemmy crystals from the Chilas area near Nanga Parbat, Pakistan. The settings differ too: the lazurite sheet calls lazurite a contact metamorphic mineral in limestones, while the lazulite sheet gives metamorphic quartzites, schists and quartz veins, the border zones of complex granite pegmatites, and alluvium.
Related pages. The sodalite group, including haüyne, is covered on the species pages; imitations of lapis are on how to tell if lapis lazuli is real. The rest of the collecting section is at the collecting guides. We hold no catalogue and nothing here is offered for sale; the wanted list is the only commercial route.