Plattnerite

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Plattnerite
Galena-Quartz-136082.jpg
Quartz and galena sample, plattnerite over the large galena cube.
General
Category Oxide minerals
Formula
(repeating unit)
PbO2
Strunz classification 04.DB.05
Crystal symmetry Tetragonal ditetragonal dipyramidal
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
Color Dark brown, iron-black
Crystal habit Prismatic crystals, may be nodular or botryoidal, fibrous and concentrically zoned, massive
Crystal system Tetragonal
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 [1][2][3]

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.

Occurrence[edit]

Plattnerite is found in numerous arid locations in North America (US and Mexico), most of Europe, Asia (Iran and Russia), Africa (Namibia) and Southern and Western Australia. It occurs in weathered hydrothermal base-metal deposits as hay-like bundles of dark prismatic crystals with a length of a few millimeters; the bundles grow on, or sometimes within various minerals,[4] including cerussite, smithsonite, hemimorphite, leadhillite, hydrozincite, rosasite, aurichalcite, murdochite, limonite, pyromorphite, wulfenite, calcite and quartz.[2]

Properties and applications[edit]

Crystal structure

Basic properties of plattnerite were described in 1845.[5] Already then, the mineral was known under its name, given to honor Karl Friedrich Plattner (1800–1858), professor of metallurgy and assaying at the Mining Academy in Freiberg, Saxony, Germany.[3]

Its crystal structure was refined later on synthetic samples. Plattnerite belongs to the rutile mineral group. It has tetragonal symmetry, space group P42/mnm (No. 136), Pearson symbol tP6, lattice constants a = 0.491 nm, c = 0.3385 nm, Z = 2 (two formula units per unit cell).[6]

Lead dioxide is used in lead acid batteries and electrochemistry, but only in synthetic form – both plattnerite and scrutinyite are too rare and find no practical application.[7]

References[edit]

  1. ^ Plattnerite at Webmineral
  2. ^ a b Plattnerite at Mindat
  3. ^ a b Handbook of Mineralogy
  4. ^ Plattnerite Gallery at Mindat
  5. ^ Haidinger W (1845) Zweite Klasse: Geogenide. II. Ordnung. Baryte VII. Bleibaryt. Plattnerit., p. 500 in Handbuch der Bestimmenden Mineralogie Bei Braumüller and Seidel Wien pp. 499-506 (in German)
  6. ^ Harada, H.; Sasa, Y.; Uda, M. (1981). "Crystal data for β-PbO2". Journal of Applied Crystallography 14 (2): 141. doi:10.1107/S0021889881008959. 
  7. ^ François Cardarelli (2008). Materials Handbook: A Concise Desktop Reference. Springer. p. 573. ISBN 1-84628-668-9. 

External links[edit]