Stolzite
Stolzite, Pb(WO4): tetragonal lead tungstate, hardness 2.5 to 3, density 8.34, the tungsten partner of wulfenite and dimorphous with raspite. Sheet data.
Stolzite is lead tungstate, Pb(WO4) on the IMA list: tetragonal, hardness 2.5 to 3, measured density 8.34, reddish brown to yellow with a white streak. It is the tungsten partner of wulfenite, Pb(MoO4). Their cells differ by 1.03% in volume, so the heavier tungsten atom makes stolzite about 22.7% denser by calculation.
In short
- The species. The September 2026 IMA-CNMNC Master List writes stolzite Pb(WO4), status G, 1845, with Czech Republic / Germany as the country. The Handbook of Mineralogy sheet writes PbWO4: tetragonal, dipyramidal crystals to 6 cm, hardness 2.5 to 3, density 8.34 measured and 8.408 calculated, uniaxial (−), streak white. A 20.00 g piece reads 17.60 g in water.
- The same-box check. Worked from each sheet’s cell, stolzite’s unit cell is 360.28 cubic ångströms and wulfenite’s 356.61, 1.03% apart, with four formula units in each. PbWO4 weighs 455.04 per formula and PbMoO4 367.15, 23.94% apart: the 87.89 difference between tungsten and molybdenum. So the calculated densities are 8.389 and 6.838, and nearly all of the gap is the atom, not the packing.
- Wulfenite on its own sheet. Wulfenite is hardness 2.75 to 3 and density 6.5 to 7.5, so a 20.00 g piece reads 16.92 to 17.33 g in water. Its Chillago, Australia, analysis is Pb(Mo0.5W0.5)O4, halfway to stolzite, and both minerals were described in the same 1845 book, pages 499 and 504, per the IMA list.
- Documented failure: the window between them. The 1:1 Chillago composition works out at 7.657 on wulfenite’s cell, 17.39 g in water for 20.00 g, between wulfenite’s printed top (17.33 g) and stolzite (17.60 g). A reading there names neither species. Nor do the printed calculated densities fully reproduce: 8.408 against 8.389 for stolzite, and wulfenite’s lowest calculated 6.88 against 6.838 for PbMoO4.
- Raspite and Sainte-Lucie. Raspite is the other PbWO4: monoclinic, density 8.46, and its sheet says it inverts to stolzite above 410 °C. The stolzite sheet names large crystals in the Sainte-Lucie mine, Lozère, France, and localities from Caldbeck Fells to Broken Hill and Tsumeb.
| Mineral or composition | Formula | System, cell volume (ų) | Formula mass | Density worked from cell | Density printed | 20.00 g piece in water | Hardness |
|---|---|---|---|---|---|---|---|
| Stolzite | Pb(WO4) | Tetragonal, 360.28 | 455.04 | 8.389 | 8.34 meas.; 8.408 calc. | 17.60 g (8.34) | 2.5–3 |
| Raspite | Pb(WO4) | Monoclinic, 357.47 | 455.04 | 8.455 | 8.46 meas.; 8.45 calc. | 17.64 g (8.46) | 2.5–3 |
| Chillago composition (wulfenite sheet, anal. 2 and ideal col. 3) | Pb(Mo0.5W0.5)O4 | Wulfenite cell, 356.61 | 411.09 | 7.657 | Not printed separately | 17.39 g (7.657) | — |
| Wulfenite | Pb(MoO4) | Tetragonal, 356.61 (I41/a cell) | 367.15 | 6.838 | 6.5–7.5 meas.; 6.88–7.48 calc. | 16.92–17.33 g (6.5–7.5) | 2.75–3 |
What is stolzite? Lead tungstate, Pb(WO4)
Stolzite is Pb(WO4) on the September 2026 IMA list, status G, grandfathered, 1845, with Czech Republic / Germany as the country of first description. The first reference is Haidinger’s Handbuch der Bestimmenden Mineralogie (Braumüller and Seidel, Wien, 1845), page 499, and the second Mineralogical Magazine 72 (2008), 987. The Handbook of Mineralogy stolzite sheet writes the formula PbWO4 and says it is dimorphous with raspite.
What the sheet records. Tetragonal, point group 4/m, space group I41/a on synthetic material, a = 5.4695 and c = 12.0432 Å, Z = 4. Crystals are commonly dipyramidal {111}, {101}, with {011}, {112} and {001}, and over 30 other forms recorded; they may be flat tabular {001}, {101}, to 6 cm. Cleavage imperfect on {001}, indistinct on {011}; fracture conchoidal to uneven; brittle; hardness 2.5 to 3. Reddish brown, brown, yellowish grey, smoky grey, straw-yellow or lemon-yellow, and may be green, orange or red; streak white; lustre resinous to subadamantine; uniaxial (−), ω 2.27, ε 2.18 to 2.19.
The analysis. Broken Hill, Australia: WO3 51.34, MnO 0.78, PbO 47.44, total 99.56, against the ideal PbWO4 column of 50.95 and 49.05, which the script reproduces exactly. Recast, it is 0.96 lead and 0.05 manganese per tungsten, 1.01 together. The sheet calls stolzite an uncommon mineral in the oxidised zone of hydrothermal tungsten-bearing lead deposits, with raspite, cerussite, anglesite, pyromorphite and mimetite.
Stolzite or wulfenite? The same-box check
Same space group, nearly the same cell, a heavier atom. Both sheets print a tetragonal I41/a cell with Z = 4: stolzite a 5.4695, c 12.0432; wulfenite a 5.436, c 12.068 Å. Worked, the volumes are 360.28 and 356.61 cubic ångströms, 1.03% apart. The formulas are 455.04 and 367.15, 23.94% apart, the whole difference being tungsten (183.84) for molybdenum (95.95). On the cells the calculated densities are 8.389 for PbWO4 and 6.838 for PbMoO4, a ratio of 1.227.
What that means at the bench. The wulfenite sheet prints a measured density of 6.5 to 7.5 and the stolzite sheet 8.34. Worked as 20 − 20/D, a 20.00 g piece reads 16.92 to 17.33 g in water as wulfenite and 17.60 g as stolzite, on the method at how to measure specific gravity at home. Hardness does not separate them: 2.75 to 3 against 2.5 to 3. Nor does streak, white on both. The printed optics differ: wulfenite ω 2.405, ε 2.283; stolzite ω 2.27, ε 2.18 to 2.19.
Documented failure: tungsten in wulfenite. The wulfenite sheet’s Chillago analysis is Pb1.00(Mo0.50W0.50)O4.00, and its third column prints that 1:1 composition as an ideal. Worked on wulfenite’s cell it is 7.657, 17.39 g in water, between the two species. A piece in that window needs an analysis. The sheets print no density for such intermediate material, so the figure is arithmetic, not a measurement. A second failure: the sheets’ own calculated densities do not quite reproduce, 8.408 printed against 8.389 worked for stolzite, and 6.88 at the bottom of wulfenite’s calculated range against 6.838 worked for PbMoO4.
Stolzite and raspite: two crystal structures for PbWO4
The IMA list has two rows written Pb(WO4), found by a field scan of the formula column and confirmed by a token search: stolzite (G, 1845) and raspite (G, 1897, Australia). The stolzite sheet says the two are dimorphous. The raspite sheet gives monoclinic, P21/a, perfect {100} cleavage, hardness 2.5 to 3, density 8.46 measured and 8.45 calculated (8.455 worked from its cell), adamantine, biaxial (+), with α and β 2.27 and γ 2.30.
Which way the change runs. The raspite sheet says raspite inverts to stolzite above 410 °C, names stolzite first among its associates, and describes raspite from the Proprietary mine at Broken Hill, among other places. Its Broken Hill analysis has WO3 48.32 and PbO 49.06 with 1.43 of Fe2O3 and MnO. Worked, raspite’s cell is 0.78% smaller than stolzite’s, so for the same formula it calculates denser: 8.455 against 8.389.
Does stolzite fluoresce?
It may, on its sheet’s wording. The stolzite sheet prints: “May fluoresce bright red to red-orange under LW UV and lemon-yellow under SW UV.” A ligature-aware search of the wulfenite and raspite sheets finds no fluorescence statement on either; the positive controls, hemimorphite and willemite, both match. This page gives no activator or cause, because no fetched source here states one.
Where the family is covered. The calcium tungstate is scheelite, whose response is set out on is scheelite fluorescent; the wulfenite sheet’s silence is on is wulfenite UV reactive, and its chemistry on is wulfenite radioactive. Why minerals glow at all is on fluorescent minerals explained. Ultraviolet exposure limits are those of the ICNIRP 2004 ultraviolet guidelines; this page gives no lamp or safety advice.
Where is stolzite found? Sainte-Lucie and the sheet’s list
Distribution, as printed. At many localities in small amounts. From Cínovec (Zinnwald), Czech Republic; Bleiberg, Carinthia, Austria; large crystals in the Sainte-Lucie mine, Saint-Léger de Peyre, Lozère, France; La Tala, Salamanca Province, Spain; several mines in Caldbeck Fells, Cumbria, England; fine examples from Broken Hill, New South Wales; Yaogangxian, Hunan, China; the Kramat Pulai mine, Perak, Malaysia; the Sumidoro gold placers, Minas Gerais, Brazil; Diko Ajuba, Nigeria; Djebel Aouam, Morocco; large crystals from Tsumeb, Namibia; and in the USA the Reef, Primos and Cohen mines in Cochise Co. and large crystals at the Fat Jack mine, Yavapai Co., Arizona, the Thompson mine, Inyo Co., California, the Emma mine, Utah, and the Black Pine mine, Montana.
Shared with wulfenite. By script over the two Distribution fields, Bleiberg and Tsumeb appear on both. The stolzite sheet marks no type locality; the IMA list gives Czech Republic / Germany, and the name honours Dr Joseph Alexis Stolz of Teplice, who provided the first specimen. The term is explained at what is a type locality.
Lead. Stolzite is 45.53% lead by mass, worked from Pb(WO4). Handling and hazard questions go to toxic minerals in a collection; this page is not safety advice. More species are in the species index. We hold no catalogue and nothing here is offered for sale; the wanted list is the only commercial route.