PROFILPELAJAR.COM

Scrutinyite

Scrutinyite
General
CategoryOxide mineral
FormulaPbO2
IMA symbolSny[1]
Strunz classification4.DB.20
Crystal systemOrthorhombic
Crystal classDipyramidal (mmm)
H–M Symbol: (2/m 2/m 2/m)
Space groupPbcn
Unit cella = 4.91 Å, b = 5.95 Å
c = 5.43 Å; Z = 4
Identification
Formula mass239.20 g/mol
ColorDark reddish brown
Crystal habitCrystalline, platy
Cleavage{100} perfect, {010} imperfect
FractureBrittle
LusterSub-metallic
StreakDark brown
DiaphaneityTransparent to translucent
Specific gravity9.867 (calculated)
Optical propertiesBiaxial
Refractive indexn > 2
Other characteristicsNon-fluorescent, nonmagnetic
References[2][3][4][5]

Scrutinyite /ˈskruːtɪni.aɪt/ is a rare oxide mineral and is the alpha crystalline form of lead dioxide (α-PbO2), plattnerite being the other, beta form. The mineral was first reported in 1988 and its name reflects the scrutiny and efforts required to identify it from a very limited amount of available sample material.[2][4]

Identification

The synthetic orthorhombic form of lead dioxide, α-PbO2, was known from 1941. Although natural lead dioxide has been known, as the mineral plattnerite (β-PbO2), since 1845,[6] its alpha form could only be recognized in 1981 and reliably identified in 1988.[4]

The new mineral was spotted in several samples collected at Bingham, New Mexico and Mapimí, Durango, Mexico. It was first thought to be minium (lead tetroxide mineral) because of its high lead content, brown color and association with other lead oxide minerals plattnerite and murdochite. Its holotype specimen consisted of crystalline plates 25–30 micrometers (μm) across and 1–2 μm thick with the total weight below 1 mg. The flakes were collected from a fluorite, quartz, limonite and rosasite matrixes. Identification and characterization of scrutinyite by the standard X-ray diffraction (XRD) technique was hindered by scarcity of material and strong signal interference with plattnerite. The unusual amount of effort required for the analysis resulted in its name derived from the word "scrutiny". The holotype specimen is preserved in the US National Museum (catalog number NMNH 165479).[2][4]

Characterization

Crystal structure

The PbO2 composition of scrutinyite was deduced by energy-dispersive X-ray spectroscopy. Slight oxygen deficiency is generally attributed to the surface effects, especially in thin samples, namely oxygen in the surface layers of PbO2 is usually substituted by the hydroxyl groups.[4]

The crystal structure was deduced by XRD as orthorhombic, space group Pbcn (No. 60), Pearson symbol oP12, lattice constants a = 0.497 nm, b = 0.596 nm, c = 0.544 nm, Z = 4 (four formula units per unit cell) were in reasonable agreement with previous results obtained on synthetic samples.[4]

References

  1. ^ Warr, L.N. (2021). "IMA–CNMNC approved mineral symbols". Mineralogical Magazine. 85 (3): 291–320. Bibcode:2021MinM...85..291W. doi:10.1180/mgm.2021.43. S2CID 235729616.
  2. ^ a b c Barthelmy, Dave. "Scrutinyite Mineral Data". www.webmineral.com.
  3. ^ "Scrutinyite: Scrutinyite mineral information and data". www.mindat.org.
  4. ^ a b c d e f J. E. Taggard Jr.; et al. (1988). "Scrutinyite, natural occurrence of α-PbO2 from Bingham, New Mexico, U.S.A., and Mapimi, Mexico" (PDF). Canadian Mineralogist. 26: 905.
  5. ^ "Handbook of Mineralogy" (PDF). arizona.edu.
  6. ^ "Handbuch der bestimmenden Mineralogie" (PDF). Retrieved June 3, 2025.

Content Disclaimer

Informasi ini disarikan dari Wikipedia dan disajikan kembali untuk tujuan edukasi. Konten tersedia di bawah lisensi CC BY-SA 3.0. Kami tidak bertanggung jawab atas ketidakakuratan data yang bersumber dari kontribusi publik tersebut.

  1. The information displayed on this website is sourced in part or in whole from Wikipedia and has been adapted for the purpose of restating it. We strive to provide accurate and relevant information, however:
  2. There is no guarantee of absolute accuracy. Wikipedia is an open, collaborative project that can be edited by anyone, so information is subject to change.
  3. It is not intended to constitute professional advice. The content displayed is for informational and educational purposes only. For important decisions (e.g., medical, legal, or financial), please consult a professional.
  4. Content copyright. Wikipedia is licensed under the Creative Commons Attribution-ShareAlike License (CC BY-SA). This means that content may be reused with appropriate attribution and shared under a similar license.
  5. Responsible use. Any risk arising from the use of information from this website is entirely the responsibility of the user.