8 Advancing Mineral Science and Exploring Planetary Surfaces: In Honor of MSA Dana Medalist, Elizabeth B. Rampe, Part I

This session honors MSA Dana Medalist Elizabeth B. Rampe, celebrating her contributions to Martian mineralogy and planetary science. We invite studies on in-situ and orbital planetary observations, lab/field data integration, and analog materials for extraterrestrial exploration.Sarah Simpson

Sunday, 19 October 2025
8:00 AM - 12:00 PM
HBGCC, 214C

Investigation of Ammoniated Clays and Altered Materials for Understanding the Nitrogen Cycle on Asteroids and Perhaps Mars

Paper number: 8-10
Program: Technical Sessions
Time: 10:20 AM – 10:35 AM

Authors

Abstract

Nitrogen is an essential element for life and ammonia-bearing clays on Ceres, Ryugu and Bennu represent intriguing geochemical conditions on these bodies. Nitrogen is also present on Mars although its form is not yet known. We are investigating the spectral properties of a suite of ammoniated smectite clays and a collection of NH4+-treated clay mixtures and alteration products in order to advance our understanding of how ammonia-bearing clays form on asteroids and potentially on Mars as well. Smectites require an interlayer cation to balance the charge in the mineral structure and NH4+ can be readily exchanged for the normally present Na+ and Ca2+ cations. For this study we have characterized the spectral properties of several NH4+-treated Al-smectites (montmorillonite), Fe-smectites (nontronite, ferruginous smectite), and Mg-smectites (saponite, hectorite). NH4+ bands are observed in reflectance spectra of our samples near 1.55, 2.01, 2.12, 3.06, 3.29, and 3.53 µm, although the band centers vary slightly in some cases depending on the octahedral cation. The NH4+ bands near 2.12 and 3.06 µm are the strongest and would be easiest to detect in spectra acquired of planetary bodies. The band near 3.06 µm currently has had the best coverage in spectral data of asteroids and is similar to features observed at Ceres. Serpentines, carbonates, and hydrocarbons are also observed on Ceres, but the NH4+ bands appear to be connected to smectites there.

Additional experiments are analyzing the presence of NH4+ incorporated in smectites, other clay minerals, clay mixtures, carbonates, and altered volcanic materials through NH4Cl brine experiments. Asteroids including Ceres, Bennu, and Ryugu include serpentine as the primary clay mineral, with smaller amounts of smectite. NH4+ spectral bands consistent with NH4+ bands in smectites are observed for these planetary bodies although the smectite abundances appear to be lower. Further, NH4+ is not readily incorporated into serpentines in the lab because it lacks the charged interlayer region present in smectites. For these reasons we are investigating the possibility of more aggressive brine treatments to produce ammoniated materials as well as ammoniated smectite-serpentine mixtures and other altered materials.

Identifying ammonia supports understanding the N cycle and will improve our knowledge of planetary processes (e.g., impacts and reduction) that could have fixed N into a bioavailable form such as ammonia.

Geological Society of America Abstracts with Programs. Vol. 57, No. 6

doi: 10.1130/abs/2025AM-413309

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