Clay templates in Ediacaran vendotaeniaceans: Implications for the taphonomy of carbonaceous fossils

Although rare, sedimentary deposits containing exceptionally preserved fossils (i.e., Lagerstätten) have shaped our view on the history of life at particular intervals, such as those recording the Cambrian radiation of animals. Therefore, understanding the processes that lead to the fossilization of unmineralized tissues is crucial to better interpret these fossil assemblages. A key issue on the fossilization of exceptionally preserved fossils is linked to the role of clay minerals in the high-fidelity preservation of recalcitrant and soft tissues. Here, we show for the first time, an association of unusual fibrous clays with carbonaceous fossils (Vendotaenia) in the late Ediacaran Tamengo Formation (Mato Grosso do Sul State, western Brazil). The vendotaeniaceans occur in laminated mudstones/siltstones interpreted as being deposited in outer to distal mid-ramp depositionary settings. The fossils are characterized by ribbon-shaped compressions 0.56 mm in mean width. The fibrous clays are obliquely oriented with respect to the bedding plane, and follow the orientation of tectonically deformed structures. Our mineralogical, geochemical, and petrographic data demonstrate that these clays are mainly composed of chlorite-smectite mixed layered minerals, with >50% chlorite. Altogether, our results suggest that these fibrous minerals formed in the late-diagenetic zone to lower anchizone, reinforcing the previous idea that clay minerals associated with fossils are not necessarily related to the preservation of soft tissues. Instead, the initial preservative pathway in our fossils was probably restricted to organic matter conservation in reducing fine-grained sediments, similar to other deposits with carbonaceous fossils. This newly established mechanism, which involves the formation of clays on organic templates in the late-diagenetic zone, is likely a more widespread phenomenon than previously thought.

Portable Raman Spectrometer for In Situ Analysis of Asbestos and Fibrous Minerals

Asbestos inhalation is associated with fatal respiratory diseases and raises concerns from the perspective of workplace safety and environmental impacts. Asbestos and asbestos-like minerals naturally occur in rocks and may become airborne when outcrops or soils are disturbed by anthropic activities. In situ detection of these minerals is a crucial step for the risk evaluation of natural sites. We assess here whether a portable Raman spectrometer (pRS) may be used in the identification of asbestos and asbestos-like minerals at the mining front during exploitation. pRS performance was tested at three geologically different mining sites in Italy and New Caledonia and compared with a high-resolution micro-Raman spectrometer (HRS). About 80% of the overall in situ analyses at the mining front were successfully identified by pRS, even when intermixed phases or strongly disaggregated and altered samples were analyzed. Chrysotile and tremolite asbestos, asbestos-like antigorite, and balangeroite were correctly detected during surveys. The major difficulties faced during in situ pRS measurements were fluorescence emission and focussing the laser beam on non-cohesive bundles of fibers. pRS is adequate for discriminating asbestos and asbestos-like minerals in situ. pRS may support risk assessment of mining sites to better protect workers and environment.

Quantitative Analysis of Asbestos-Containing Materials Using Various Test Methods

The advantages of X-ray powder diffraction (XRPD) analysis are its non-destructive nature, reliability, fast and easy sample preparation, and low costs. XRPD analysis has been used for mineral identification and the quantitative/qualitative determination of various types of fibrous minerals in asbestos-containing materials (ACMs). In order to test the detection limit of ACMs by XRPDD, standard samples with various concentrations of ACMs (0.1%, 1%, and 3%) were fabricated using three matrix materials (talc, vermiculite, and sepiolite). Asbestiform tremolite and chrysotile were identified in the XRPD profiles of the samples with 1% and 3% ACMs. Their integral intensities were positively correlated with the concentrations. However, the XRPD peak of asbestos was not found in the samples with 0.1% ACMs. Therefore, scanning and transmission electron microscopy were utilized to investigate the samples with a very low concentration of ACMs. Although the ACM concentration (0.1%) was negligible and its direct observation was time-consuming, electron microscopy allowed for the detection of asbestos in several matrix materials. Thus, a combination of XRPD and electron microscopy improve analytical performance and data reliability.

Biosignatures in Subsurface Filamentous Fabrics (SFF) from the Deccan Volcanic Province, India

The morphology, chemical, and mineralogical composition of subsurface filamentous fabrics (SFF) from the Deccan Volcanic Province (DVP) were investigated to determine the origin of these spectacular aggregates. SFF occur in a wide variety of morphologies ranging from pseudo-stalactites to irregular fabrics and are classified as SFFIr (irregular) or SFFMa (matted). The SFF samples exhibit a thread-like (or filament-like) center from which mineral precipitation starts to form the final macroscopic morphologies. Detailed investigations revealed organic material (fungal chitin) in the innermost filamentous core, which may have acted as an initial nucleus for the mineralization processes. The morphometric characteristics of certain filamentous fabrics are very similar to those of microbial filaments and the fabrics formed from them but are clearly distinct from similar types of non-biological precipitates (fibrous minerals, speleothems, and “chemical gardens”). These features indicate that the filamentous cores might be products of microbial communities that were active in the basaltic cavities. The SFF cross-sections display similar concentric layers of the mineral succession and reach thicknesses of several centimeters with spectacular lengths up to 100 cm and constant diameters. The typical mineralization sequence points to temporal variation in the chemical composition of the mineralizing fluids from Fe(Mg)-rich (Fe-oxides/-hydroxides, Fe-rich sheet silicates such as celadonite and di-/tri-smectite) to Ca-dominated (Ca-rich zeolites) and finally pure SiO2 (opal-CT, chalcedony, and macro-crystalline quartz). Assuming biological activity at least during the early mineralization processes, circumneutral pH conditions and maximum temperatures of 100–120 °C were supposed. The formation of filamentous cores including Fe-bearing phyllosilicates probably occurred near the surface after cooling of the lava, where the elements necessary for mineral formation (i.e., Si, Mg, Al, Fe) were released during alteration of the volcanic host rocks by percolating fluids.

The Mineralogical Composition of Samos Zeoliitic Rocks and their potential use as Feed Additives and Nutrition Supplements

Fifteen (15) zeolitic rocks from Karlovassi-Marathokampos basin of Samos Island (Greece) were investigated for their mineralogical composition by X-Ray Diffraction (XRD) method. According to EU Regulation No 651/2013, clinoptilolite of sedimentary origin with ≥80 wt% clinoptilolite, ≤20 wt% clay minerals, free of fibres and quartz, can be used as feed additive for all animal species. Depending on the zeolites, the zeolitic rocks are grouped to those containing: Clinoptilolite (33-86 wt%), clinoptilolite (59 wt%) + mordenite (20-21 wt%), clinoptilolite (22 wt%) + analcime (29 wt%), clinoptilolite (17 wt%) + phillipsite (27 wt%), analcime (29-70 wt%), mordenite (62%) and chabazite (63 wt%). None of the clinoptilolite-containing rocks (10 samples) meet the requirements of the EU Regulation No 651/2013, and thus cannot be used as feed additives for all animal species and consequently as nutrition supplements, since all of them contain 2-5 wt% quartz, two of them 20-21 wt% mordenite (fibrous zeolite), nine of them <80 wt% clinoptilolite (17-73 wt%) and two of them >20 wt% clay minerals (27-42 wt%). Although the EU Regulation No 651/2013 refers to clinoptilolite of sedimentary origin, using the presence or absence of quartz and fibrous minerals, none of the five mordenite, analcime and chabazite containing zeolitic rocks, can be used as feed additives and nutrition supplements, since all of them contain 2-6 wt% quartz and one of them contains 62 wt% mordenite (fibrous zeolite).

Mineralogical Characteristics of Carbonate Rock-Hosted Naturally Occurring Asbestos from Republic of Korea

&lt;p&gt;Naturally occurring asbestos (NOA) occurs in rocks and soils as a result of natural weathering and human activities. It is proved that inhalation of asbestos fibers can lead to increase risk of developing several diseases such as lung cancer and malignant mesothelioma. The parent rocks of asbestos have been mainly associated with (ultra)mafic and carbonate rock. The previous studies on NOA were mainly limited to (ultra)mafic rock-hosted asbestos in S. Korea, but studies on carbonate rock-hosted asbestos are relatively rare in S. Korea. Therefore, this study was aimed to examine mineralogical characteristics of carbonate rock-hosted NOA. Types of rocks at the several sites mainly consisted of Precambrian metasedimentary rocks, carbonate rock, and Cretaceous and Jurassic granites. Asbestos-containing carbonate rock samples were obtained for mineralogical characterization. XRD, PLM, EPMA, SEM and EDS analyses were used to characterize mineralogical characteristics of the carbonate rock-hosted NOA. From the carbonate rock, fibrous minerals were occurred acicular and columnar forms in the several sites. Fibrous minerals were composed of mainly tremolite, actinolite, and associated minerals included possibly asbestos containing materials (ACM) such as talc, vermiculite, and sepiolite. The length and aspect ratios of tremolite and actinolite were similar to the standard asbestiform (length &gt;5 &amp;#13211;, length:width = 3:1). These results indicate that both non-asbestiform and asbestiform tremolite and actinolite with acicular forms occurred in carbonate rocks at several sites. Geological and geochemical characteristics and mineral assemblages indicate tremolite and associated minerals might be formed by hydrothermal alternation and/or hydrothermal veins of carbonate rocks due to intrusion of acidic igneous rocks.&lt;/p&gt;

A Comparison of Environmental Concerns in Two Disparate Montana and Nevada Communities

Asbestos refers to six fibrous minerals that occur naturally in the environment in the United States and throughout the world. Deposits may be found in soil, rocks, and deposits of other minerals such as vermiculite and talc. These naturally occurring asbestos (NOA) minerals belong to the serpentine and amphibole family of minerals. This chapter reports shared components of community-driven environmental concerns related to exposure to NOA in a rural Montana and a suburban Nevada community. The specific aim is to establish an understanding of the community and community member's primary concern(s) related to NOA in both communities. The knowledge that NOA is commonly found in areas across the United States supports the need for additional research into the health effects of environmental exposure and best-practices to reduce exposure risk while allowing communities to thrive economically.

Micro-Raman Spectroscopy, a Powerful Technique Allowing Sure Identification and Complete Characterization of Asbestiform Minerals

Micro-Raman spectroscopy has been applied to fibrous minerals regulated as “asbestos”—anthophyllite, actinolite, amosite, crocidolite, tremolite, and chrysotile—responsible of severe diseases affecting mainly, but not only, the respiratory system. The technique proved to be powerful in the identification of the mineral phase and in the recognition of particles of carbonaceous materials (CMs) lying on the “asbestos” fibers surface. Also, erionite, a zeolite mineral, from different outcrops has been analyzed. To erionite has been ascribed the peak of mesothelioma noticed in Cappadocia (Turkey) during the 1970s. On the fibers, micro-Raman spectroscopy allowed to recognize many grains, micrometric in size, of iron oxy-hydroxides or potassium iron sulphate, in erionite from Oregon, or particles of CMs, in erionite from North Dakota, lying on the crystal surface. Raman spectroscopy appears therefore to be the technique allowing, without preparation of the sample, a complete characterization of the minerals and of the associated phases.

Assessment of Serpentine Group Minerals in Soils: A Case Study from the Village of San Severino Lucano (Basilicata, Southern Italy)

Naturally occurring asbestos (NOA) is a generic term used to refer to both regulated and un-regulated fibrous minerals when encountered in natural geological deposits. These minerals represent a cause of health hazard, since they have been assessed as potential environmental pollutants that may occur both in rocks and derived soils. In the present work, we focused on the village of San Severino Lucano, located in the Basilicata region (southern Apennines); due to its geographic isolation from other main sources of asbestos, it represents an excellent example of hazardous and not occupational exposure of population. From the village and its surroundings, we collected eight serpentinite-derived soil samples and carried out Differential Scanning Calorimetry (DSC), Derivative Thermogravimetric (DTG) and Transmission Electron Microscopy with Energy Dispersive Spectrometry (TEM-EDS), in order to perform a detailed characterization of serpentine varieties and other fibrous minerals. Investigation pointed out that chrysotile and asbestos tremolite occur in all of the samples. As for the fibrous but non-asbestos classified minerals, polygonal serpentine and fibrous antigorite were detected in a few samples. Results showed that the cultivation of soils developed upon serpentinite bedrocks were rich in harmful minerals, which if dispersed in the air can be a source of environmental pollution.