Chlorite topography and dissolution of the interlayer studied with Atomic Force Microscopy

Journal Article · Wed Jan 01 00:00:00 EST 2014 · American Mineralogist

DOI:https://doi.org/10.2138/am.2014.4478· OSTI ID:1126960

Gazze, Salvatore ^[1]; Stack, Andrew G ^[2]; Ragnarsdottir, K. Vala ^[3]; McMaster, Terence ^[4]

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1. University of Bristol, United Kingdom
2. ORNL
3. University of Iceland, Institute of Earth Sciences
4. University of Bristol and Bristol Centre for Functional Nanomaterials, United Kingdom

Chlorite has a structure composed of a combination of two distinct layers, the tetrahedral15 octahedral-tetrahedral (TOT) and the interlayer (i.e. the octahedral layer between TOT layers). In this study, the morphology and dissolution of chlorite in pure water has been visualized using Atomic Force Microscopy. Upon cleavage, the TOT layer shows atomically flat terraces and steps, while the interlayer presents strips and voids. In pure water, dissolution channels and equilateral, mono-oriented triangular etch pits form in the interlayer and lead to progressively increased solubilisation. Dissolution channels are proposed to originate from structural defects, while a conceptual model is discussed to explain the presence of triangular etch pits. In this model, their formation is driven by the different reactivity of the two octahedral configurations along the etch pits. It is not currently known which of these is the most stable configuration, however we propose arguments that point towards a specific orientation. The conceptual model is supported by experimental data and is potentially applicable to all mineral structures constituted by continuous octahedral layers.

• Research Organization: Oak Ridge National Lab. (ORNL), Oak Ridge, TN (United States)
• Sponsoring Organization: USDOE Office of Science (SC)
• DOE Contract Number: DE-AC05-00OR22725
• OSTI ID: 1126960
• Journal Information: American Mineralogist, Vol. 99, Issue 1; ISSN 0003--004X
• Country of Publication: United States
• Language: English