Is witherite fluorescent?
Yes. The Handbook sheet says fluorescent and phosphorescent under UV but gives no colour; all 9 FMS records list white under shortwave, and 5 of 9 an afterglow.
Yes. The Handbook witherite sheet says fluorescent and phosphorescent under UV, X-rays and electron beams, but prints no colour. All 9 Fluorescent Mineral Society records of witherite list a white glow under shortwave, 4 also under longwave, and 5 of 9 an afterglow. Witherite is BaCO3, hardness 3 to 3.5, density 4.22 to 4.31.
In short
- The sheet says yes, without a colour. The Handbook of Mineralogy witherite sheet reads: Fluorescent and phosphorescent under UV, X-rays, and electron beams. It does not name a band, a colour or a share of specimens. Witherite is Ba(CO3) on the IMA-CNMNC Master List, hardness 3 to 3.5, density 4.22 to 4.31; the species page is witherite.
- The nine-record check. The Fluorescent Mineral Society’s FMDB witherite page linked 9 specimen records on 12 November 2026, all read by script. Every one lists witherite fluorescence: shortwave in 9 of 9, longwave in 4, midwave in 4. Every shortwave and longwave line is white; the one other colour is a green midwave line on a Rosiclare, Illinois piece.
- Afterglow is common. 5 of the 9 records list a witherite afterglow after shortwave: white in 3, blue in 1, green in 1; the Rosiclare piece lists white after all three bands. That fits the sheet’s phosphorescent, and the sheet gives no colour to check it against.
- Documented failure: the neighbours glow too. 5 of the 9 records list other minerals glowing on the same piece: barytocalcite pink in 4, calcite red, yellow or white in 4, fluorite blue in 2, baryte yellow in 1. On one Rampgill mine piece calcite is white under shortwave as well, so a white shortwave glow does not by itself pick out the witherite.
- Lamps, barium and labels. A lamp shows luminescence, not identity: the barytocalcite, calcite, baryte and fluorite sheets all print fluorescence too. Telling witherite from baryte is on witherite. UV exposure limits are in the ICNIRP 2004 guidelines on limits of exposure to ultraviolet radiation; that is not safety advice.
| Band or mineral | Records | Fluorescence colour (lines) | Afterglow (lines) | Handbook sheet wording |
|---|---|---|---|---|
| Witherite, shortwave (254 nm lamp, 255 nm LED) | 9 of 9 | White 9 | 5: white 3, blue 1, green 1 | Fluorescent and phosphorescent under UV, X-rays, and electron beams |
| Witherite, longwave (365 nm LED) | 4 of 9 | White 4 | 1: white | No band named |
| Witherite, midwave (305 nm) | 4 of 9 | White 3, green 1 | 1: white | No band named |
| Barytocalcite, same pieces | 4 of 9 | Pink (shortwave 4, midwave 3, longwave 1) | — | Pale yellowish to red fluorescence under SW and LW UV |
| Calcite, same pieces | 4 of 9 | Shortwave red 2, yellow 1, white 1; midwave yellow 2 | — | May fluoresce red, blue, yellow, and other colors under either SW and LW UV |
| Fluorite, same pieces | 2 of 9 | Blue (shortwave 2, midwave 1, longwave 1) | — | Fluoresces blue, violet, green, yellow, red under UV |
| Baryte, same piece | 1 of 9 | Yellow (shortwave) | — | May fluoresce and phosphoresce cream to spectral colors under UV |
Does witherite glow under UV light? What the sheet says
The wording. Under Physical Properties the witherite sheet prints, after hardness and density: Fluorescent and phosphorescent under UV, X-rays, and electron beams. The search that finds it is ligature-aware: on older sheets pdftotext turns the fl ligature into a stray glyph, so the stem uoresc is searched case-insensitively, with the hemimorphite and willemite sheets as positive controls that must match. The witherite sheet prints the word in plain text.
What it does not say. No colour, no shortwave or longwave, no share of specimens and no cause. Its occurrence note is low-temperature hydrothermal veins, typically as an alteration product of baryte, with baryte, fluorite, calcite and galena as associates; mixed pieces make up 5 of the 9 records below. The witherite page sets witherite in the aragonite group with aragonite, strontianite and cerussite; aragonite’s own lamp records are on is aragonite fluorescent.
What the nine FMDB records show
Method. The FMDB witherite page linked 9 specimen records on 12 November 2026; all 9 were saved and read by script. Each record’s Summary of luminescence responses has a block per mineral; the script took the Witherite block, tallied its lines by kind (fluorescence or afterglow), band and colour, and listed the other minerals in the same summary. The records are dated July 2025 to May 2026.
Result. Witherite fluorescence appears in all 9: shortwave 9, longwave 4, midwave 4, and every shortwave and longwave line reads white. The single non-white line is midwave green on the Rosiclare record, which lists white under shortwave and longwave. Four records come from the Rampgill mine, Nenthead, Alston Moor, and four from Hardin Co., Illinois (Cave-in-Rock and Rosiclare), two districts the witherite sheet’s Distribution names; the ninth is from Danby Level, Arkengarthdale, North Yorkshire. Nine records from three districts are a small, chosen sample, not a rate for witherite in general.
Why a white glow is not proof: the neighbour check
Who else glows. Five of the nine records are mixed pieces. Barytocalcite, BaCa(CO3)2, is credited pink in four, all from the Rampgill mine; its sheet prints pale yellowish to red under SW and LW UV. Calcite appears in four, red twice and yellow or white under shortwave; its sheet prints may fluoresce red, blue, yellow, and other colors. Fluorite is blue in two; one North Yorkshire piece credits baryte yellow.
Where the check fails. On one Rampgill mine record the calcite is white under shortwave too, the same colour and band as the witherite beside it, so a white shortwave patch on a mixed North Pennine piece is not a determination. The lamp narrows the question; the identification rests on the methods on witherite, which this page does not repeat. Calcite’s lamp behaviour is covered on is calcite UV reactive.
Does witherite phosphoresce?
The sheet and the records agree. The sheet says phosphorescent; 5 of the 9 records list an afterglow after shortwave, white in 3, blue in 1 and green in 1, and one lists afterglow after longwave and midwave as well. The other 4 list none, which in a contributor’s record means none was reported, not that none exists. The FMDB descriptions offer causes for some responses; this page does not repeat them.
Lamps and hazards, in one line each. Test under both bands and note each result with the locality; lamp types are compared on the best UV lamp for mineral collecting and the physics is on fluorescent minerals explained. UV exposure limits between 180 and 400 nm are in the ICNIRP 2004 guidelines on limits of exposure to ultraviolet radiation; barium-mineral questions are routed to toxic minerals in a collection; this page is not safety or health advice. More guides are in the collecting guides. We hold no catalogue and nothing here is offered for sale; the wanted list is the only commercial route.