Plattnerite
Plattnerite is an oxide mineral and is the beta crystalline form of lead dioxide (β-PbO2), scrutinyite being the other, alpha form. It was first reported in 1845 and named after German mineralogist Karl Friedrich Plattner. Plattnerite forms bundles of dark needle-like crystals on various minerals; the crystals are hard and brittle and have tetragonal symmetry.
| Plattnerite | |
|---|---|
| General | |
| Category | Oxide minerals |
| Formula (repeating unit) | PbO2 |
| IMA symbol | Ptn |
| Strunz classification | 4.DB.05 |
| Crystal system | Tetragonal |
| Crystal class | Ditetragonal dipyramidal (4/mmm) H–M Symbol: (4/m 2/m 2/m) |
| Space group | P42/mnm |
| Unit cell | a = 4.95 Å, c = 3.38 Å; Z = 2 |
| Identification | |
| Formula mass | 239.20 g/mol |
| Color | Dark brown, iron-black |
| Crystal habit | Prismatic crystals, may be nodular or botryoidal, fibrous and concentrically zoned, massive |
| Twinning | Contact and penetration twinning on {011}, rarely polysynthetic |
| Cleavage | None |
| Fracture | Sub-conchoidal, fibrous |
| Tenacity | Brittle |
| Mohs scale hardness | 5.5 |
| Luster | Bright metallic to adamantine |
| Streak | Chestnut brown |
| Diaphaneity | Subtranslucent to opaque |
| Specific gravity | 8.5–9.63, average = 9.06 |
| Optical properties | Uniaxial (-) |
| Refractive index | nω=2.35, nε=2.25 |
| Birefringence | δ = 0.1 |
| Alters to | tarnishes to dull on exposure |
| Other characteristics | Non-fluorescent, nonmagnetic |
| References | |
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