Carbon mineralisation of ultramafic mine tailings can reduce net emissions of anthropogenic carbon dioxide by reacting Mg-silicate and hydroxide minerals with atmospheric CO₂ to produce carbonate minerals. We investigate the controls on carbonate mineral formation at the derelict Woodsreef chrysotile mine (New South Wales, Australia). Quantitative XRD was used to understand how mineralogy changes with depth into the tailings pile, and shows that hydromagnesite [Mg₅(CO₃)₄(OH)₂·4H₂O], is present in shallow tailings material (<40 cm), while coalingite [Mg₁₀Fe³⁺₂(CO₃)(OH)₂₄·2H₂O] and pyroaurite [Mg₆Fe³⁺₂(CO₃)(OH)₁₆·4H₂O] are forming deeper in the tailings material. This indicates that there may be two geochemical environments within the upper ∼1 m of the tailings, with hydromagnesite forming within the shallow tailings via carbonation of brucite in CO₂-rich conditions, and pyroaurite and coalingite forming under more carbon limited conditions at depth. Radiogenic isotope results indicate hydromagnesite and pyroaurite have a modern (F¹⁴C > 0.8) atmospheric CO₂ source. Laboratory-based anion exchange experiments, conducted to explore stable C isotope fractionation in pyroaurite, shows that pyroaurite δ¹³C values change with carbon availability, and ¹³C-depleted signatures are typical of hydrotalcites in C-limited environments, such as the deep tailings at Woodsreef. Quantitative XRD and elemental C data estimates that Woodsreef absorbs between of 229.0–405.1 g CO₂ m⁻² y⁻¹.

超镁铁矿尾矿的碳矿化可通过使硅酸镁和氢氧化镁矿物与大气CO ₂反应生成碳酸盐矿物，从而减少人为二氧化碳的净排放量。我们调查了废弃的Woodsreef温石棉矿（澳大利亚新南威尔士州）对碳酸盐矿物形成的控制。X射线定量分析用于了解矿物学如何随尾矿堆中深度的变化而变化，并表明在浅尾矿物质（<40 cm）中存在菱镁矿[Mg ₅（CO ₃）₄（OH）₂ ·4H ₂ O]，而煤[Mg ₁₀ Fe ³⁺ ₂（CO ₃）（OH）₂₄·2H ₂ O]和焦铁矿[Mg ₆ Fe ³⁺ ₂（CO ₃）（OH）₁₆ ·4H ₂ O]在尾矿中形成得更深。这表明在尾矿的上〜1 m范围内可能存在两个地球化学环境，在浅尾矿中，水镁石是在富CO _2的条件下通过水镁石的碳化而在浅尾矿中形成的，并且在深度上碳含量更高的条件下会形成焦铁矿和煤成矿。放射性同位素结果表明菱镁矿和焦铝铁矿具有现代的（F ¹⁴ C> 0.8）大气CO ₂资源。基于实验室的阴离子交换实验，进行探索pyroaurite稳定Ç同位素分馏，显示，pyroauriteδ ¹³ C值，碳的可用性发生变化，和¹³ C-耗尽签名是典型的水滑石的在C-有限的环境，如深尾矿在Woodsreef。定量XRD和元素C数据估计，Woodsreef的吸收量为229.0–405.1 g CO ₂  m ^-2 y ^-1。