Hyperspectral cathodoluminescence of REE-bearing zirconosilicate minerals from Pajarito Mountain, USA

Agpaites are rare igneous rock types containing minerals abundant in high field strength elements (HFSE), rare earth elements (REE), and a variety of other critical metals, making them potentially important resources for critical raw materials. New Mexico (USA) hosts the layered Pajarito Mountain agpaitic complex (PMAC), which is prospective for Y and Zr hosted in abundant eudialyte as a primary cumulus phase. Hyperspectral cathodoluminescence (HyCL) shows that low luminescent minerals such as eudialyte have spectra in the infrared (e.g. 1.37 eV and 1.40 eV), suggesting the presence of Nd3+. Eudialyte has been altered to Ca-zirconosilicate minerals, like gittinsite, which are highly luminescent and contains distinct light and dark CL zones. The lighter zones have much higher counts and peaks from ~2.0 eV to ~4.0 eV and may be related Eu3+, Sm3+, and/or Tb3+ to whereas the darker zones show an anomalous, prominent doublet at 1.25 eV and 1.26 eV. Hyperspectral CL imaging, spectral deconvolution, and activator identification provide valuable insights into zirconosilicate chemistry, elemental zonation, and potential element mobility related to alteration, especially regarding highly luminescent and critical metals such as the REE.