Is sodalite the same as lapis lazuli?
No. Sodalite is a mineral, density 2.27 to 2.33, white streak, no pyrite; lapis is a rock, GIA SG 2.50 to 3.00. In water, 20 g of sodalite reads under 12 g.
No. Sodalite is a single mineral, hardness 5.5 to 6, density 2.27 to 2.33, with a white streak. Lapis lazuli is a rock of mainly lazurite, calcite and pyrite (GIA), specific gravity 2.75 ± 0.25. A 20.00 g sodalite weighs 11.19 to 11.42 g in water on its sheet; no sodalite figure read here reaches GIA's lapis floor of 12.00 g.
In short
- One mineral against one rock. The Handbook sodalite sheet describes a single cubic mineral. The GIA lapis lazuli page calls lapis an aggregate of several minerals, mainly lazurite, calcite and pyrite. The International Gem Society adds that lapis can contain sodalite, so sodalite can be part of lapis, but a piece of sodalite is not lapis.
- The 12-gram line. Worked as 20 − 20/SG, a 20.00 g piece reads 11.19 to 11.42 g in water as sodalite on its sheet, and no more than 11.67 g on the gem society’s widest sodalite range. GIA’s lapis range, 2.50 to 3.00, reads 12.00 to 13.33 g. Under 12.00 g is outside GIA’s lapis; it is not proof of sodalite.
- Pyrite before the scale. The gem society says both may carry white calcite but sodalite lacks pyrite inclusions; GIA says golden pyrite flecks give lapis its sparkle. A blue stone with brassy flecks is pointing at lapis; one without them has decided nothing.
- Where the line fails, documented. Kondo and Beaton (Gems & Gemology, 2009) measured a hackmanite at 2.44 because it held nepheline: 11.80 g, only 0.20 g under the line. Pure lazurite, 11.60 to 11.84 g, also falls below it, so the line separates sodalite from lapis rock as GIA measures it, not from lazurite. Dyed jasper and synthetic lapis have no density in the sources fetched here, so the line says nothing about them.
- Streak decides, but not on a finished stone. Sodalite’s streak is white and lazurite’s bright blue on their sheets. The gem society says streak and acid tests on lapis are destructive and for a professional gemmologist only. The rock question is on is lapis lazuli a mineral or a rock.
| Material | What it is (source) | Hardness | Density or SG | 20.00 g piece in water | Against the 12.00 g line | Streak | Pyrite flecks | Choose this name when |
|---|---|---|---|---|---|---|---|---|
| Sodalite | One mineral (sheet) | 5.5–6 | 2.27–2.33 | 11.19–11.42 g | Under | White | Lacks them (IGS) | Blue, white streak, no pyrite, under the line |
| Sodalite, wider range | IGS properties panel | 5.5–6 (IGS) | 2.14–2.40 | 10.65–11.67 g | Under | Not printed | Lacks them (IGS) | As above |
| Hackmanite, 15 of 16 stones | Sodalite variety (Kondo and Beaton) | Not tested | 2.26–2.31 | 11.15–11.34 g | Under | Not tested | Not reported | Sodalite that changes colour in light |
| Hackmanite with nepheline | Kondo and Beaton, sample 4 | Not tested | 2.44 | 11.80 g | 0.20 g under | Not tested | Not reported | Sodalite, with a mixed reading |
| Lapis lazuli | A rock: lazurite, calcite, pyrite (GIA) | 5–6 (IGS) | 2.75 ± 0.25 (GIA) | 12.00–13.33 g | On or over | Light blue (IGS) | Often (GIA, IGS) | The rock, with calcite or pyrite |
| Lapis lazuli, gem | IGS properties panel | 5–6 | 2.7–2.9 | 12.59–13.10 g | Over | Light blue | Often | As above |
| Lazurite | The blue mineral of lapis (sheet) | 5–5.5 | 2.38–2.45 | 11.60–11.84 g | Under: the line cannot catch it | Bright blue | Not part of the mineral | A single blue mineral with a blue streak |
| Haüyne | Sodalite-group mineral (sheet) | 5.5–6 | 2.44–2.50 | 11.80–12.00 g | Under, or on it | Slightly bluish to colourless | Not part of the mineral | Blue grains in phonolite and related rocks |
| Calcite | The white in both (sheet; IGS) | 3 | 2.7102 | 12.62 g | Over | White | — | White veins and patches |
| Pyrite | The golden flecks in lapis (sheet; GIA) | 6–6.5 | 5.018 | 16.01 g | Over | Greenish black to brownish black | — | Brassy metallic flecks |
| Dyed jasper, “Swiss lapis” | A dyed imitation (IGS) | Not fetched | Not fetched | Not worked | Not tested | Not fetched | No | Never lapis |
| Synthetic lapis | Made by Pierre Gilson and Carroll Chatham (IGS) | Not fetched | Not fetched | Not worked | Not tested | Not fetched | With or without (IGS) | Never natural lapis |
Is sodalite the same as lapis lazuli? The criteria
Four criteria decide it, in this order. What it is: sodalite is one mineral, lapis a rock. Inclusions: pyrite points to lapis. Weight: sodalite is light enough to sit under a line that GIA’s lapis never falls below. Streak: white against blue, but only where a destructive test is acceptable.
What each source says. The gem society’s sodalite article says sodalite belongs to the sodalite group with haüyne, lazurite and nosean, that all are found in lapis lazuli, and that sodalite and haüyne can also occur separately. GIA names lazurite, calcite and pyrite as the three major minerals of lapis and lazurite as the source of its blue. So sodalite may be one ingredient of a lapis; a blue stone that is all sodalite is still not lapis lazuli.
Why the question comes up. The gem society says sodalite, natural or synthetic, can simulate lapis, and that because lapis is better known, you are more likely to meet sodalite offered as lapis, in error or in a deliberate effort to mislead. It calls sodalite the only natural gemstone available large enough and deep enough blue to be a convincing lapis simulant. The species data are on sodalite and lazurite.
Sodalite vs lapis lazuli by weight: the 12-gram line
The 12-gram line: a 20.00 g blue piece that weighs less than 12.00 g in water is below GIA’s whole range for lapis lazuli, and every sodalite figure read here falls below it. GIA gives lapis 2.75 ± 0.25, so 2.50 to 3.00, which worked as 20 − 20/SG is 12.00 to 13.33 g. The gem society’s gem lapis, 2.7 to 2.9, is 12.59 to 13.10 g.
Where sodalite falls. The Handbook gives 2.27 to 2.33: 11.19 to 11.42 g, 0.58 g under the line at its top. The gem society gives 2.14 to 2.40 and about 2.28 for massive blue material: 10.65 to 11.67 g and 11.23 g. Kondo and Beaton measured 15 of their 16 stones at 2.26 to 2.31, 11.15 to 11.34 g. Weighing in water is set out on how to measure specific gravity at home.
Why calcite does not rescue a sodalite. Treated as a two-mineral mix, sodalite at 2.27 to 2.33 would need 44.7% to 52.2% calcite by volume to reach 2.50. Such a piece would show about as much white as blue. Pyrite moves the reading faster, 6.3% to 8.4% by volume, but the gem society says sodalite lacks pyrite. These are model bounds, not analyses.
Where the 12-gram line fails
Mixed sodalite, documented. GIA’s 2009 paper recorded one Burmese hackmanite at SG 2.44, against a published sodalite range of 2.15 to 2.35, and explained it by a large nepheline content identified by Raman; nepheline, it says, is 2.55 to 2.65. That stone reads 11.80 g, within 0.20 g of the line. A sodalite rock with more nepheline could cross it, so a reading just over 12.00 g is not proof of lapis.
Pure lazurite. Lazurite itself, 2.38 to 2.45, reads 11.60 to 11.84 g, under the line. The line separates sodalite from lapis as GIA measures the rock; it does not separate sodalite from a clean lazurite crystal. On the sheets, three properties do: streak, white against bright blue; refractive index, 1.483 to 1.487 against 1.502 to 1.522; and density, 11.19 to 11.42 g against 11.60 to 11.84 g in water, a margin of 0.18 g that the gem society’s wider sodalite range (to 11.67 g) and GIA’s nepheline-rich stone (11.80 g) both close. Of the three, the streak is the one those overlaps do not touch. Haüyne, up to 2.50, reaches the line exactly.
Imitations. The gem society lists enamel, glass, plastic, dyed howlite, and dyed jasper misleadingly called “Swiss lapis”, and records synthetic lapis by Pierre Gilson and Carroll Chatham, with or without pyrite. No density for these was in the sources fetched for this page, so the line is not applied to them; they are covered on how to tell if lapis lazuli is real and how to tell if a crystal is dyed.
Which name is wrong for which piece
“Lapis lazuli” is wrong for a uniform blue stone with no pyrite that reads under 12.00 g in water for 20.00 g: that is the sodalite pattern. It is also wrong for dyed jasper and for synthetic lapis, which are imitations, whatever they weigh.
“Sodalite” is wrong for a stone with brassy pyrite flecks through it, and for a single blue crystal with a bright blue streak, which is lazurite. It is incomplete for a hackmanite, which is sodalite that changes colour in light; that is tested on is sodalite UV reactive.
“Lazurite” is wrong for the rock: lapis lazuli is the name for the aggregate, and lazurite for the mineral in it. The rock-or-mineral question is answered on is lapis lazuli a mineral or a rock, and the other identification guides are in the collecting guides. Nothing on this site is offered for sale; the wanted list is the only commercial route.