CaltechAUTHORS
Published July 2022 | Version public
Journal Article Metadata-only

Håleniusite-(Ce), CeOF, the Ce Analogue of Håleniusite-(La) from the Água de Pau Volcano, Sãn Miguel Island, Azores District, Portugal

Creators

  • 1. ROR icon Natural History Museum of Los Angeles County
  • 2. ROR icon California Institute of Technology

Abstract

Håleniusite-(Ce) (IMA2021-042), CeOF, is a new mineral discovered in ejectum from the Água de Pau volcano, Sãn Miguel Island, Azores District, Portugal. It occurs as opaque, cream-colored, fine-grained pseudomorphic replacements of hexagonal tablets of bastnäsite-(Ce). It is associated with astrophyllite and fluornatropyrochlore in a matrix composed mainly of albite, quartz, and aegirine. The mineral has a white streak and a calculated density of 5.890 g/cm³ for the empirical formula. The strongest powder diffraction lines are [d_(obs)Å(I_(obs))(hkl)]: 3.247(100)(111), 2.840(31)(200), 2.004(46)(220), and 1.705(42)(311). Electron probe microanalysis provided the empirical formula (Ce₀.₄₁La₀.₂₁Sm₀.₁₅Nd₀.₀₄Eu₀.₀₃Ca₀.₀₂Y₀.₀₂Dy₀.₀₂Gd₀.₀₁)_(Σ0.91)(O₀.₇₀F₀.₃₀)F₁.₀₀. Håleniusite-(Ce) has a fluorite-type structure, space group Fm3̅ m, with a = 5.6597(10) Å and V = 181.29(10) ų (Z = 4).

Additional Information

Reviewers Dan Holtstam and Henrik Friis are thanked for their constructive comments on the manuscript. This study was funded, in part, by the John Jago Trelawney Endowment to the Mineral Sciences Department of the Natural History Museum of Los Angeles County.

Additional details

Identifiers

Eprint ID
117462
Resolver ID
CaltechAUTHORS:20221017-12657600.23

Funding

John Jago Trelawney Endowment

Dates

Created
2022-10-21
Created from EPrint's datestamp field
Updated
2022-10-25
Created from EPrint's last_modified field