Plattnerite

What is plattnerite? Lead dioxide in the rutile group

Plattnerite is PbO2, a black, heavy, tetragonal lead oxide that the Handbook places in the rutile group. The Handbook of Mineralogy plattnerite sheet gives point group 4/m 2/m 2/m and commonly prismatic crystals parallel to [001], showing {010}, {011}, {110}, {131} and {001}, to 5 mm; it may be nodular or botryoidal, fibrous and concentrically zoned, or massive. Twinning is on {011}, as contact and penetration twins, rarely polysynthetic. It is brittle, hardness 5.5, density 9.564 measured and 9.563 calculated; no cleavage is printed. It is opaque to slightly translucent, jet-black, iron-black or brownish black, yellowish in transmitted light, with a chestnut-brown streak and a bright metallic to adamantine lustre that tarnishes dull on exposure.

What the IMA list records. The September 2026 IMA-CNMNC Master List row reads plattnerite, PbO2, status G (grandfathered), 1845, United Kingdom. On standard atomic weights PbO2 is 239.20 g/mol and 86.62% lead; the sheet’s one analysis, from the Ojuela mine, Mexico, by electron microprobe, prints PbO2 99.6 and CuO 0.1. The sheet names it for Carl Friedrich Plattner (1800–1858), Professor of Metallurgy and Assaying at the Mining Academy, Freiberg, where its type material is kept, number 10045. It marks no type locality; see what a type locality is.

The rutile-group cell. Its space group, P42/mnm, is the one the rutile and cassiterite sheets print, each also in the rutile group. Plattnerite’s cell is the largest of the three: 41.53 ų per formula unit against 35.78 ų for cassiterite and 31.22 ų for rutile, worked from each sheet’s a and c.

Plattnerite or scrutinyite? One formula, two cells

Plattnerite and scrutinyite are dimorphs: both are PbO2. A script over the September 2026 IMA list for the formula PbO2, cross-checked by a raw line scan, finds exactly 2 rows: plattnerite (G, 1845, United Kingdom) and scrutinyite (A, 1984-061, USA). Each Handbook sheet prints “Dimorphous with” the other. The scrutinyite sheet heads its formula α-PbO2 and gives an orthorhombic cell, space group Pbcn, a = 4.971, b = 5.956, c = 5.438 Å, Z = 4.

The dimorph cell check. Plattnerite’s cell, 4.9525² × 3.3863 = 83.06 ų with Z = 2, gives 2 × 239.20 ÷ (0.60221 × 83.06) = 9.564, the measured density to the third decimal. Scrutinyite’s, 4.971 × 5.956 × 5.438 = 161.00 ų with Z = 4, gives 9.868, against the 9.867 its sheet prints; its density has not been measured. Per formula unit scrutinyite occupies 40.25 ų and plattnerite 41.53 ų, so the orthorhombic form is 3.08% more compact.

Documented failure: the Ojuela overlap. The plattnerite sheet names the Ojuela mine, Mapimí, Durango, and the Mex-Tex mine, near Bingham, New Mexico; the scrutinyite sheet names both too, and lists plattnerite as an associate at the Sunshine #1 mine, New Mexico, and at Mapimí. Scrutinyite is dark reddish brown to clove-brown with a dark brown streak and submetallic lustre, in crystals to 30 µm, and its sheet says the name alludes to the close examination necessary to recognise it. A 20.00 g piece would read 17.91 g in water as plattnerite and 17.97 g as scrutinyite, a 0.06 g gap. A dark PbO2 crust from Ojuela or Bingham is a candidate for either until it has been examined.

Why is plattnerite black when other lead oxides are red or yellow? The lead-oxide ledger

Of the five IMA rows made only of lead and oxygen, the two PbO2 dimorphs are the dark ones, and the others are red, scarlet or yellow. The script finds litharge, PbO (G, 1917), and massicot, PbO (G, 1841); minium, written Pb4+Pb2+2O4 (G, 1806); and plattnerite and scrutinyite, PbO2. Their sheets give litharge as red, massicot as sulfur-yellow to orpiment-yellow with a yellow streak, minium as scarlet to brownish red with a yellow-orange streak, plattnerite as jet-black with a chestnut-brown streak, and scrutinyite as dark reddish brown with a dark brown streak.

What the ledger does and does not say. It is a colour and streak ledger read off five sheets, not an explanation: no sheet gives a cause for any of these colours, and this page offers none. It does give the collector a sorting rule within these five: a black or dark brown lead oxide with a brown streak points to PbO2, while a red, scarlet or yellow earthy lead oxide points to the other three. Plattnerite is also the hardest of the four printed hardnesses, 5.5 against 2 to 2.5; scrutinyite’s is n.d. Hardness method: how to test mineral hardness properly.

Lead by mass. Worked from the formulas, the dioxides are 86.62% lead, minium 90.67%, and litharge and massicot 92.83%. The two dioxides are the least lead-rich of the five by mass because they carry the most oxygen per lead.

Where is plattnerite found? Leadhills first, then the arid oxidised zones

The plattnerite sheet’s Distribution opens with Leadhills, Lanarkshire, and Wanlockhead, Dumfriesshire, Scotland. Then the Tchah Milleh mine, near Anarak, and the Dareh Zandjir mine, near Anjireh, Iran; Tsumeb, Namibia; large masses from the Coeur d’Alene district, Shoshone Co., and the Democrat mine, Lemhi Co., Idaho; the Goodsprings district and the Diamond mine near Eureka, Nevada; the 79 mine, the Defiance mine at Gleeson, the Glove mine and elsewhere in Arizona; the Mex-Tex mine and Granite Gap, New Mexico; and the Ojuela mine, Mapimí, and Santa Eulalia, Mexico. The Scottish locality page is Leadhills and Wanlockhead.

How it forms. The sheet says plattnerite occurs in weathered hydrothermal base-metal deposits, oxidized typically in arid climates, with cerussite, smithsonite, hemimorphite, leadhillite, hydrozincite, rosasite, aurichalcite, murdochite, pyromorphite, wulfenite, calcite and quartz. It is named as an associate on the wulfenite sheet as well.

Plattnerite is 86.62% lead by mass; lead is covered on toxic minerals in a collection, and this page is not health or safety advice. Related species are at the species index. We hold no catalogue and nothing here is offered for sale; the wanted list is the only commercial route.

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