Lanarkite
Lanarkite is Pb2O(SO4): grey to pale green, white streak, hardness 2 to 2.5, density 6.92, flexible in thin laminae. Leadhills, Scotland, and in smelter slag.
Lanarkite is a lead oxide sulphate, Pb2O(SO4), a Leadhills, Scotland, species dated 1832 on the IMA list: monoclinic, grey to pale green or pale yellow, white streak, hardness 2 to 2.5, measured density 6.92, flexible in thin laminae, and fluorescent yellow under longwave UV. It is 78.72% lead by mass. Three of its Handbook localities are smelter slag.
In short
- Leadhills, 1832. The September 2026 IMA-CNMNC Master List lists Pb2O(SO4), status G, 1832, United Kingdom. The Handbook of Mineralogy sheet prints the same formula; its Name field reads, in full, for the occurrence in the Susanna mine, Lanarkshire, Scotland. Type material is at the Natural History Museum, Paris.
- The two-to-one check. Pb2O(SO4) is anglesite, Pb(SO4), plus one more PbO. Worked from the sheet’s Leadhills analysis, 84.63% PbO and 15.37% SO3, the molar ratio is 1.98 : 1; the ideal is 2 : 1, and anglesite’s is 1 : 1. The ideal column, 84.79% PbO, is reproduced exactly.
- Not the most lead-rich in its own company. Of the six minerals in the table, lanarkite and its five associates on the sheet, hydrocerussite carries the most lead by mass, 80.14%; lanarkite is second at 78.72%, cerussite 77.54%. The formula arithmetic is in the table.
- The slag clause. The sheet’s Distribution field names lanarkite in slag at 3 places: the Meadowfoot smelter near Wanlockhead, Laurium in Greece, and the Argent mines in South Africa. A lanarkite label from a smelter site is consistent with the sheet.
- Telling it from the other white lead minerals. Weight and UV will not do it; that trap is set out on the leadhillite page. Habit does: lanarkite’s crystals are elongated and flexible in thin laminae, against cerussite’s very brittle twins. Lead minerals are covered on toxic minerals in a collection; this page gives no health or handling advice, and none of it is advice.
| Species | IMA formula | IMA status, year | Lead by mass, worked | Hardness | Density (measured) | Tenacity | Streak | Leadhills or Wanlockhead on the sheet |
|---|---|---|---|---|---|---|---|---|
| Lanarkite | Pb2O(SO4) | G, 1832 | 78.72% | 2 to 2.5 | 6.92 | Flexible in thin laminae | White | Susanna mine; Meadowfoot smelter slag |
| Hydrocerussite | Pb3(CO3)2(OH)2 | G, 1877 | 80.14% | 3.5 | 6.80 to 6.82 | Brittle | Not printed | Wanlockhead and Leadhills |
| Cerussite | Pb(CO3) | G, 1845 | 77.54% | 3 to 3.5 | 6.55 | Very brittle | White | Leadhills |
| Leadhillite | Pb4(SO4)(CO3)2(OH)2 | G, 1832 | 76.82% | 2.5 to 3 | 6.55 | Sectile | Not printed | Leadhills and Wanlockhead |
| Susannite | Pb4(SO4)(CO3)2(OH)2 | G, 1845 | 76.82% | Not determined | Not determined (6.52 calculated) | Not printed | Not printed | Susanna mine, Leadhills |
| Caledonite | Cu2Pb5(SO4)3(CO3)(OH)6 | G, 1832 | 64.22% | 2.5 to 3 | 5.6 to 5.76 | Brittle | Pale green | Leadhills and Wanlockhead |
What is lanarkite? A lead oxide sulphate from Leadhills
The names. The September 2026 IMA-CNMNC Master List gives Pb2O(SO4), status G, 1832, United Kingdom; the Handbook sheet prints the same formula. Its Name field, verbatim: for the occurrence in the Susanna mine, Lanarkshire, Scotland. We add no derivation to that. The species whose sheet names it for the Susanna mine itself is susannite. Lanarkite is not linarite, the blue lead-copper sulphate named for Linares in Spain; see linarite.
What it looks like. Crystals to 5 cm, elongated along one axis with many forms, sometimes in radial aggregates, and massive. Twinning is rare. One cleavage is perfect and three are imperfect, and thin laminae are flexible. Colour grey, pale green or pale yellow; streak white; lustre adamantine to resinous and pearly on cleavage surfaces. The sheet says it fluoresces yellow under X-rays and longwave UV; the lamp question in general is on fluorescent minerals explained.
Two honest gaps on the sheet. Its cell data are from synthetic material, and its powder pattern is labelled with a question mark, [Scotland?]. The calculated density, 7.08, is higher than the measured 6.92. We report both and pick neither; the in-water figure, 17.11 g for 20.00 g, uses the measured value, as the leadhillite page does.
Why is lanarkite Pb2O(SO4)? The two-to-one check
The arithmetic. On standard atomic weights (Pb 207.2, S 32.06, O 15.999), Pb2O(SO4) has a formula mass of 526.46, of which 78.72% is lead. Written as oxides it is two PbO to one SO3: 84.79% PbO and 15.21% SO3, the sheet’s ideal column to the hundredth. Anglesite, Pb(SO4), is one to one.
The check on real material. The sheet’s analysis is from Leadhills: 84.63% PbO and 15.37% SO3, recalculated to 100% after deducting an ignition loss of 0.83% from an original total of 98.66%. Dividing each by its molar mass (PbO 223.20, SO3 80.06) gives a ratio of 1.98 : 1, within about 1% of two to one. Because the figures were recalculated to 100%, the check confirms the proportion, not the original analytical total.
Where the arithmetic stops. A ratio cannot be measured at home, and lead content does not single lanarkite out: in the table, hydrocerussite is 80.14% lead, and cerussite 77.54%. What a collector can see is in the sheets’ habit and tenacity fields: lanarkite flexible in thin laminae, hardness 2 to 2.5; cerussite very brittle, 3 to 3.5; hydrocerussite brittle, 3.5, with a perfect basal cleavage. The hardness method is on how to test mineral hardness properly.
Lanarkite in slag: what the sheet records
The slag clause. A script over the sheet’s Distribution field finds the word slag 3 times: at the Meadowfoot smelter, near Wanlockhead, Dumfriesshire, in slag; at Laurium, Greece, in slag; and from the Argent Pb–Zn mines, about 100 km east of Johannesburg, Transvaal, South Africa, in slag. The rest are named as mines, districts or places. A lanarkite labelled from a smelter is therefore consistent with the reference. Slag minerals at Laurium are discussed on Lavrion.
Where else, per the sheet. In Scotland, large crystals from the Susanna mine, Leadhills; see Leadhills and Wanlockhead. In England, several mines in Caldbeck Fells, Cumbria, and the Gravel Hill mine, Perranzabuloe, Cornwall. In Wales, the Frongoch mine, Dyfed. Then Giepenbach in the Harz, the Herrensegen mine and Badenweiler in the Black Forest; the Silberleiten mine, Tirol; the Laquorre mine, Ariège; the Tchah Milleh mine, Iran; the Ediacara lead mine, South Australia; the Leadville district, Colorado; the C & B mine, Arizona; and the Buena Esperanza mine, Challacollo, Chile.
Its company. The sheet calls lanarkite a rare secondary mineral in the oxidised zone of lead sulphide deposits, associated with cerussite, leadhillite, susannite, hydrocerussite and caledonite. Lead minerals are covered on toxic minerals in a collection; this page gives no health or handling advice, and none of it is advice. The rest of the reference section is at the species index. We hold no catalogue and nothing here is offered for sale; the wanted list is the only commercial route.