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The main structural building blocks that form manganese oxides are MnO6 octahedra; these share corners and edges to construct specific structures, which can either be tunneled or layered. In the layered structures, that is, phyllomanganates, the MnO6 octahedra form sheets, which, in turn, alternate with sheets of metal oxides and H2O. These metal ions can vary (Zn, Co, Ni, Al, Li, ...) and give rise to an entire range of different metal oxides. The characterization of these layered materials is important as they have various economical/industrial applications. Birnessite‐type materials, a specific type of layered manganese oxides, are widely studied for their use as cathode materials in alkali‐ion batteries. Phyllomanganates are also commonly found as constituents in sediments and soils or as coatings on rock surfaces. Their natural occurrence as black colored components have ensured that these minerals were also applied as pigments in archaeological and historical contexts. They are, for example, often found in rock art paintings and on pottery. As the oxides are used in unique archaeological objects, Raman spectroscopy is an evident choice for characterization due to its non‐destructive nature of analysis. In the current study, five mineral samples of (layered) manganese oxides are analyzed with different Raman instrumentations, including mobile systems and a benchtop micro‐Raman setup. The characterization of each selected manganese oxide and their comparison with literature data is discussed for the micro‐Raman instrumentation. In addition, the ability of identifying and characterizing layered manganese oxides and the possible challenges when using mobile instrumentation are discussed as well. [ABSTRACT FROM AUTHOR]

Pabellón de Pica, Tarapaca, Chile, is a former guano mine exploited in the late 19th and early 20th centuries. Guano is in a direct contact with Cu sulfide mineralization leading to the formation of minerals with a highly unusual chemical composition, especially Cu‐organic complexes and nitrogen‐bearing phases. In this work, we report results of the Raman spectroscopic investigation of several unique Cu‐bearing minerals that are the result of supergene processes at the Pabellón da Pica site. We focus on several minerals with new and interesting structure types which were described from this locality for the first time, namely, antipinite (K–Na–Cu oxalate), ammineite (Cu ammine complex), chanabayaite (Cu ammine triazolate complex), and joanneumite (Cu isocyanurate). The Raman spectra contain specific bands attributed to the characteristic vibrations of the molecular groups present in the minerals (oxalate, ammine, triazolate, and isocyanurate groups) and vibrations within Cu‐centered polyhedra. A comparison was made with the vibrational spectra of related minerals and synthetic phases, which revealed substantial proliferation and shifting of numerous bands, which is in agreement with the complex composition of the investigated minerals. The results obtained appropriately complement known structural and spectroscopic data published previously. [ABSTRACT FROM AUTHOR]

Coade stone has played a significant role in architectural and ornamental design since its inception in the early 18th century. It is well known that earlier, experimental, architectural stoneware products existed, but few of these have been studied in detail scientifically, and only one major analytical study of Coade stone has appeared in the literature. This paper presents a new spectroscopic analysis of Coade stone along with that of a newly discovered sample from Oxnead Hall in Norfolk where it known that Sir Clement Paston experimented with artificial stone in the late 16th century. The results demonstrate that it is possible to differentiate between the two variants on the basis of both the raw materials used and the different phases formed in their production processes. [ABSTRACT FROM AUTHOR]

Among precious stones used in antiquity, bigi morati stand out for their importance. They consist in black limestones mainly employed in sculptures and architectural heritages and quarried from several sites through the Mediterranean area. Their provenance is difficult to assess due to their similar appearance to the naked‐eye observation and the possible confusion with black marbles (i.e., bigi antichi). Classical methods used for studying ancient marbles, such as minero‐petrographic and stable isotopes analyses (δ13C and δ 16O), resulted to be powerful in provenancing these black lithotypes. However, these methods are microdestructive and cannot be always applied in the case of precious artefacts for which sampling is not allowed. Bearing carbonaceous matter conferring them the typical black‐dark grey colour, Raman spectroscopy might support studies on these limestones, bringing important information about the structural state of organic/carbonaceous matter and their geological evolution. In this study, the potential of Raman spectroscopy in determining geological and geographic provenance of bigi morati was tested on quarry samples from six among the most famous ancient exploitation sources. The obtained results demonstrated that the use of Raman parameters typical of low‐ordered carbon matter is an effective tool in discriminating provenance. Moreover, the laboratory‐based approach lays the groundwork for future development and validation of the method for in situ measurements on artefacts by using portable equipment. [ABSTRACT FROM AUTHOR]