Mottramite
Mottramite, PbCu(VO4)(OH): orthorhombic green lead copper vanadate, hardness 3 to 3.5, density about 5.9, yellowish green streak, in a series with descloizite.
Mottramite is a lead copper vanadate, PbCu(VO4)(OH) on the IMA list (G, 1876): orthorhombic green crystals to 3 mm and drusy crusts, hardness 3 to 3.5, density about 5.9, streak yellowish green. It forms a series with descloizite: mottramite is the copper end, descloizite the zinc end. In the sheet’s Bisbee analysis copper is 98.3% of the copper plus zinc.
In short
- The copper check. Mottramite and descloizite differ in one metal: PbCu(VO4)(OH) against PbZn(VO4)(OH) on the September 2026 IMA-CNMNC Master List. Worked from the Handbook of Mineralogy analyses, copper is 98.3% of the copper plus zinc atoms at Bisbee, Arizona, and 2.9% at Abenab, Namibia. Both sheets print the same 1:1 column, CuO 9.86 and ZnO 10.08 (50.0%), as the midpoint.
- The one-metal switch. A script over the IMA list finds 6 rows that begin with Pb and end (VO4)(OH). Four of them change only the metal beside the lead: mottramite (Cu, 1876), descloizite (Zn, 1854), čechite (Fe2+, 1980) and plumbogottlobite (Mg, IMA 2025-075). The other two, bushmakinite and ferribushmakinite, carry Pb2 and a phosphate group.
- Documented failure: the colour and the balance. The sheet’s colours run from grass-green to blackish brown, overlapping descloizite’s blackish brown. Calculated densities of 6.187 and 6.202 read 16.77 and 16.78 g in water for 20.00 g. Why heft fails on this series is worked on the descloizite page and not repeated here; the streak, yellowish green against orange to brownish red, is the field test given there.
- Where. The Distribution field says many localities and names Mottram St. Andrew, Cheshire; the Mammoth-St. Anthony mine at Tiger, Bisbee, the Total Wreck, Apache and 79 mines, Arizona; the Mayflower mine, New Mexico; the Whale mine, Nevada; Mina Grande, Chile; Tsumeb and the Otavi district, where it is abundant; and Kabwe (Broken Hill), Zambia. It prints no Mexican locality.
- Lead. Worked from the formula, mottramite is 51.45% lead by mass. It is a lead mineral; lead is covered on toxic minerals in a collection and is galena toxic. This page is not safety or health advice.
| Formula or analysis | Source | CuO wt% | ZnO wt% | V2O5 wt% | PbO wt% | Copper share of Cu + Zn | Reads as |
|---|---|---|---|---|---|---|---|
| Mottramite, PbCu(VO4)(OH) | IMA list; worked | 19.75 | 0 | 22.58 | 55.43 | 100% | Mottramite |
| Bisbee, Arizona (average of three) | Mottramite sheet, analysis (1) | 17.05 | 0.31 | 21.21 | 55.64 | 98.3% | Mottramite |
| Pb(Cu,Zn)(VO4)(OH), Zn:Cu = 1:1 | Column (2) on both sheets | 9.86 | 10.08 | 22.53 | 55.30 | 50.0% | Midpoint |
| Abenab, Namibia | Descloizite sheet, analysis (1) | 0.56 | 19.21 | 22.76 | 55.47 | 2.9% | Descloizite |
| Descloizite, PbZn(VO4)(OH) | IMA list; worked | 0 | 20.12 | 22.48 | 55.18 | 0% | Descloizite |
What is mottramite? A green lead copper vanadate
Mottramite is PbCu(VO4)(OH) on the September 2026 IMA list, status G (grandfathered), 1876, country United Kingdom. The list’s reference is Canadian Mineralogist 33 (1995), 1119, the crystal-structure paper the Handbook of Mineralogy mottramite sheet cites as Cooper and Hawthorne; this page has not read it. The Handbook prints the same formula and places mottramite in the descloizite group.
On the sheet. Orthorhombic, point group 2/m 2/m 2/m, space group Pnma, as equant or dipyramidal {111} crystals, prismatic along [001] or [100], to 3 mm, in drusy crusts, botryoidal, and usually granular to compact or massive. Hardness 3 to 3.5; density about 5.9 measured and 6.187 calculated. Grass-green, olive-green, yellow-green, siskin-green, blackish brown or nearly black, with a yellowish green streak and a greasy lustre; transparent to nearly opaque. Biaxial (−), rarely (+), α 2.17, β 2.26, γ 2.32, 2V about 73°.
Its chemistry, worked. On standard atomic weights PbCu(VO4)(OH) is 51.45% lead, 15.78% copper and 12.65% vanadium by mass, or PbO 55.43%, CuO 19.75%, V2O5 22.58% and H2O 2.24%. The same arithmetic on the sheet’s 1:1 midpoint returns its printed column to within 0.01: CuO 9.85 against 9.86, ZnO 10.08, PbO 55.30, V2O5 22.53, H2O 2.23. That is the method’s positive control.
How do you tell mottramite from descloizite?
By the copper check, which needs an analysis. Both sheets say the two form a series and print the identical column (2), Pb(Cu,Zn)(VO4)(OH) with Zn:Cu = 1:1, as the halfway point. Worked in atoms, copper is 98.3% of copper plus zinc in the mottramite sheet’s Bisbee analysis, an average of three, and 2.9% in the descloizite sheet’s Abenab analysis. The IMA formulas put copper in mottramite and zinc in descloizite, so a copper-dominant analysis such as Bisbee’s matches the mottramite end and a zinc-dominant one such as Abenab’s the descloizite end.
In the hand. The descloizite page shows why the balance cannot help and gives the streak as the test that does: mottramite yellowish green, descloizite orange to brownish red, on how to use a streak plate. That page’s arithmetic is not repeated here. An intermediate streak means an intermediate composition, which is what the copper check measures.
Where the check stops. The Bisbee analysis also carries 0.50% CrO3, 0.24% P2O5 and 1.33% As2O5, and its V2O5 is 21.21% against 22.58% ideal. Chromium and phosphorus point towards vauquelinite, whose page separates the two by chemistry. The copper check names a point on the copper–zinc line; it does not show that nothing else is present.
Which minerals share mottramite’s formula pattern?
Six rows, by script. Over the September 2026 IMA list, a row parser finds 6 rows whose formula begins with Pb and ends (VO4)(OH): bushmakinite Pb2Al(PO4)(VO4)(OH), 2001-031; čechite PbFe2+(VO4)(OH), 1980-068; descloizite PbZn(VO4)(OH), G 1854; ferribushmakinite Pb2Fe(PO4)(VO4)(OH), 2014-055; mottramite PbCu(VO4)(OH), G 1876; and plumbogottlobite PbMg(VO4)(OH), 2025-075. Each was checked against its raw line.
The one-metal switch. Four of the six are PbM(VO4)(OH) and differ only in M: copper, zinc, ferrous iron, magnesium. A label that says only lead vanadate could be any of them, or vanadinite, Pb5(VO4)3Cl. Mottramite is the copper one, and an analysis is what shows it.
Is mottramite found at Tsumeb, in Mexico or at Ojuela?
Tsumeb, yes; Mexico and Ojuela, not on the sheet. The Distribution field begins many localities and names Mottram St. Andrew, Cheshire; in Arizona the Mammoth-St. Anthony mine at Tiger, Bisbee, the Total Wreck mine, the Apache mine near Globe and the 79 mine near Hayden; the Mayflower mine, Socorro Co., New Mexico; the Whale mine, Goodsprings, Nevada; Mina Grande, Arqueros, Chile; abundant at Tsumeb and elsewhere in the Otavi district, Namibia; and Kabwe (Broken Hill), Zambia. It names no Mexican locality, so this page names none, Ojuela included.
The name. The sheet gives it for an occurrence in England, ore stockpiled at Mottram St. Andrew, Cheshire, likely mined from the Pim Hill mine, Shrewsbury, Shropshire. The sheet marks no type locality and this page claims none; the term is explained on what is a type locality. The associates it lists are descloizite, duftite, mimetite, wulfenite, cerussite, azurite and dioptase.
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.