Abstract Bells is an ungrouped carbonaceous chondrite that has in recent years been proposed as a CR‐an. This link to CR chondrites has previously been identified through the analysis of anhydrous silicates, for example, oxygen isotopic compositions of olivine (Marrocchi et al., 2023). In this study, the aqueous alteration extent of Bells has been analyzed through the use of carbonate minerals to see whether Bells' aqueous history supports a CR origin. The carbonates identified were calcite grains that had O‐isotope compositions showing a single generation trend ranging from δ 18 O = +20.7 to +40.3‰, δ 17 O = +6.9 to +23.4‰ and Δ 17 O = −4.1 to +2.4. These are isotopically similar values to carbonates found in other CR‐an meteorite Al Rais (δ 18 O = +28.8 to +34.8‰ Jilly‐Rehak et al., 2018). Oxygen isotope compositions plot along a mass‐independent slope of 0.75 ± 0.12, which indicates that isotopic evolution is controlled primarily by mixing of fluid and rock reservoirs. Starting temperatures for calcite precipitation are estimated to be ~14°C. These observations here help support a potential reclassification of Bells as a CR‐an meteorite.
Riches et al. (2026) studied this question.