Is sodalite UV reactive?
Yes: its Handbook sheet records bright red-orange fluorescence under LW and SW UV. In GIA tests all 16 sodalite stones glowed under longwave; 15 changed colour.
Yes. The Handbook of Mineralogy sheet records bright red-orange fluorescence under longwave and shortwave UV, with yellowish phosphorescence, and says sodalite may be photochromic. In GIA tests on 16 Afghan and Burmese stones (Kondo and Beaton, 2009), all 16 fluoresced under longwave, and 15 changed colour after several minutes of shortwave: the tenebrescence that marks hackmanite.
In short
- The sheet’s words. The Handbook sodalite sheet reads Bright red-orange cathodoluminescence and fluorescence under LW and SW UV, with yellowish phosphorescence; may be photochromic in magentas. Both bands are named, there is no may before the fluorescence, and the afterglow and colour change are separate effects on the same line.
- GIA’s 16-stone ledger. Kondo and Beaton (Gems & Gemology, 2009) tested six Burmese and ten Afghan stones. All 16 fluoresced under longwave. After several minutes of shortwave, 15 changed colour: 4 strongly, 4 moderately, 4 weakly, 3 very weakly, and 1 not at all. They named 12 hackmanite and 4 sodalite; all 6 Burmese stones were hackmanite, against 6 of the 10 Afghan.
- The lamp-off test. With the lamp on, the glow is fluorescence. With it off, a glow that lingers and fades is phosphorescence: the Afghan stones gave several minutes of yellowish white. A body colour left deeper than before is tenebrescence, which in the 2009 tests took hours of white light to fade back. Three effects, one lamp, three observations.
- Not every sodalite-group mineral glows. Read ligature-aware, 2 of the 4 sodalite-group sheets record fluorescence: sodalite, and haüyne, reddish orange to purplish pink under longwave. Lazurite and nosean record none. The orange spots the gem society reports in lapis lazuli under longwave are therefore not explained by lazurite’s sheet.
- Documented negative. A transparent 7.17 ct sodalite GIA examined in 2021 showed the strong orange fluorescence reported for hackmanite but no colour change, perhaps, the authors say, because exposure was short. Orange under longwave does not by itself make a stone hackmanite. Exposure limits are in the ICNIRP 2004 guidelines; this page is not safety advice.
| Material | Source | Longwave (365 nm) | Shortwave (254 nm) | Afterglow (phosphorescence) | Colour change (tenebrescence) |
|---|---|---|---|---|---|
| Sodalite | Handbook sheet | Bright red-orange | Bright red-orange | Yellowish | May be photochromic in magentas |
| Sodalite and hackmanite, Afghanistan (10 stones) | Kondo and Beaton 2009 | Generally strong yellow to orange | Weak to moderate red or orange, quickly obscured by moderate to strong white to yellowish white | Moderate to strong yellowish white, several minutes after SW; weaker after LW | 6 of 10 enough to be named hackmanite |
| Hackmanite, Myanmar (6 stones) | Kondo and Beaton 2009 | Mostly weak orange; samples 1 and 2 moderate to strong orange | Host inert except sample 1, weak red; strong greenish yellow in fissures | Samples 1 and 2: very weak to weak white, about a minute after SW | 6 of 6 named hackmanite |
| Hackmanite, Dungannon Township, Ontario | IGS sodalite article | Bright yellow-orange | Bright pale pink | Not stated | May turn raspberry red after SW |
| Sodalite, general | IGS properties panel | Usually orangy red to violet | Dull pink (Guinea) | Not stated | Tenebrescence (hackmanite) |
| Haüyne | Handbook sheet | May show reddish orange to purplish pink | Not named | Not recorded | Not recorded |
| Lazurite | Handbook sheet | Nothing recorded | Nothing recorded | Not recorded | Not recorded |
| Nosean | Handbook sheet | Nothing recorded | Nothing recorded | Not recorded | Not recorded |
| Lapis lazuli (the rock) | IGS lapis panel | Orange spots or streaks (Afghanistan and Chile) | Dimmer and more pink; may fluoresce whitish | Not stated | Not stated |
| Tugtupite (comparison) | Handbook sheet | Red to rose-pink, band not named | Red to rose-pink, band not named | Phosphorescent | Photochromic: pale colours become pink in sunlight or X-rays |
Does sodalite glow under UV light? What the sheet says
Sodalite fluoresces bright red-orange under both longwave and shortwave on its Handbook sheet, and the sheet records an afterglow and a colour change as well. The full line on the Handbook of Mineralogy sodalite sheet is Bright red-orange cathodoluminescence and fluorescence under LW and SW UV, with yellowish phosphorescence; may be photochromic in magentas. Cathodoluminescence is a response to an electron beam, a laboratory effect. The sheet gives no cause for any of these, and this page supplies none.
How it was read. The sheet was typeset with an fl ligature that text extraction renders as a stray symbol, so a literal search for fluoresc misses it. The method used: fl or any single non-letter, followed by uoresc, case-insensitive, in the Physical Properties field, whitespace joined. Hemimorphite, willemite and sodalite are the positive controls; all three match, and the literal search matches none.
Across the group. The same read over the four sheets that print Sodalite group finds two that record fluorescence: sodalite, and haüyne, reddish orange to purplish pink under longwave only. The lazurite and nosean sheets record none anywhere on the sheet. Species data are on sodalite.
Longwave or shortwave for sodalite? What GIA’s 16 stones did
Longwave lit every stone. Kondo and Beaton (Gems & Gemology, 2009) examined six stones from Myanmar and ten from Badakhshan, Afghanistan, in a darkened room with a standard long- and short-wave lamp. All 16 fluoresced under longwave: the Afghan stones generally a strong yellow to orange, most Burmese stones weak orange, two of them moderate to strong orange.
Shortwave split them by locality. The Afghan stones fluoresced a weak to moderate red or orange that was quickly obscured by a stronger white to yellowish white. In the Burmese stones the host did not react to shortwave, except sample 1, a weak red; what glowed, strong greenish yellow, was in the fissures. The authors say that fracture fluorescence, with a whitish look in Afghan stones, suggested clarity enhancement, and that rough from both localities is commonly oiled. Documented failure: a shortwave glow along cracks may belong to a filler, not to the sodalite.
Afterglow. After shortwave the Afghan material phosphoresced moderate to strong yellowish white for several minutes; after longwave, more weakly for a similar time. Burmese samples 1 and 2 gave very weak to weak white for perhaps a minute. How a different blue mineral behaves is on is benitoite fluorescent; this page does not repeat its asset.
Is it fluorescence or tenebrescence? The lamp-off test
The lamp-off test: what you see under the lamp is fluorescence; a glow that fades after the lamp goes off is phosphorescence; a body colour left deeper than before is tenebrescence. Kondo and Beaton define tenebrescence as the ability to change colour in response to the application or absence of certain wavelengths of light, and say it is how gemmologists typically distinguish hackmanite. The 2021 GIA Micro-World note puts it as a reversible colour change under UV, from light purple to saturated purple in hackmanite.
How long each takes, in the published tests. In 2009, fading the stones under a household incandescent bulb or a daylight-equivalent lamp took several hours to more than a day; deepening the colour under a 4-watt shortwave lamp took several minutes. The 2023 GIA Micro-World note saw a hackmanite turn a more vivid purple after about one second under a 6-watt longwave lamp. Kondo and Beaton add that the change is reversible unless the stone is heated, and that heating above 500 °C destroys it.
The 16-stone ledger, tallied by script from the paper’s Table 1. Strong 4, moderate 4, weak 4, very weak 3, none 1. The authors named stones with weak to strong change hackmanite (12) and the rest sodalite (4), and say there are no guidelines clearly separating the two names. Fading in light generally is on which minerals fade in light; no storage or exposure recipe is offered here.
When the answer changes: lazurite, lapis and a stone that did not change
Lapis lazuli. The gem society’s lapis panel records orange spots or streaks under longwave in Afghan and Chilean lapis, dimmer and more pink under shortwave, and that it may fluoresce whitish under shortwave. It does not say which mineral glows, and lazurite’s sheet records nothing, so this page does not assign the spots. Telling the two materials apart is on is sodalite the same as lapis lazuli.
Orange is not proof of hackmanite. GIA’s 2021 note describes a 7.17 ct transparent, near-colourless sodalite with the strong orange fluorescence reported in hackmanite and no observed colour change, perhaps because exposure was short. The gem society’s sodalite article adds that Ontario hackmanite from Dungannon Township is bright pale pink under shortwave and bright yellow-orange under longwave, and may turn raspberry red after shortwave.
Another photochromic sheet. Tugtupite, a sodium beryllium aluminium silicate chloride from the Ilímaussaq intrusion, Greenland, which the sodalite sheet also names, records red to rose-pink fluorescence and phosphorescence, and its sheet calls it photochromic, with pale colours turning pink in sunlight or X-rays. Its sheet prints no mineral group, so it is a comparison here, not a relative.
Shortwave lamps and exposure: what ICNIRP sets
The specimen is not the exposure question; the lamp is. Table 1 of the ICNIRP 2004 guidelines on limits of exposure to UV radiation gives far lower limits at 254 nm than at 365 nm; the table marks both wavelengths as mercury emission lines. The arithmetic is worked on is hemimorphite UV reactive and is not repeated. This is not safety advice; read the guideline itself.
Lamps. Since sodalite responds to both bands on its sheet, and GIA’s tests used both, a longwave lamp alone shows the fluorescence but not the shortwave locality difference. Lamps are compared on the best UV lamp for mineral collecting, and why minerals fluoresce at all is on fluorescent minerals explained.
On this site. 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.