Minerals

PDF 3D: Rosa del desierto - Desert rose (Morocco)

by Francisco José López Fraile

Realizado a partir de un escaneado láser.

El PDF 3D es un formato que soporta modelos de 3D y permite interactuar con ellos: mover, rotar, medir, extraer secciones, etc. Se necesita tener instalado el software Acrobat Reader (gratuito, mínimo versión 8).

1991. Reactions forming pyrite and marcasite from solution: II Via FeS precursors below 100°C.

by Martin Schoonen

Schoonen, M.A.A., Barnes, H.L., 1991. Reactions forming pyrite and marcasite from solution: II Via FeS precursors below 100°C. Geochimica Cosmochimica Acta, 55: 1505-1514.

The formation of pyrite and marcasite from a FeS precursor has been examined experimentally. In aging experiments at... more The formation of pyrite and marcasite from a FeS precursor has been examined experimentally. In aging experiments at 65°C, the conversion of precursor amorphous FeS depends on these geologically relevant variables: concentration of sulfur-contributing species, acidity, redox state, time, Fe(II)/S(−II) ratio in solution, and addition of an organic ligand (citrate). The results indicate that pyrite and marcasite formation proceed at a significant rate only if intermediate sulfur species (i.e., polysulfides, polythionates, or thiosulfate) are present in solution. In the absence of any sulfur contributor or with only hydrogen sulfide or bisulfide present, no FeS2 formed within 16 days. Sulfidation of the precursor proceeds through progressively more sulfur-rich, Fe-S phases: am FeS (Fe1.11S-Fe1.09S) → mackinawite (FeS0.93-FeS0.96) → greigite (Fe3S4) → pyrite/marcasite FeS2. Greigite is absent under very reduced environments. The conversion sequence found in this study is in good agreement with iron-sulfide distribution patterns found in modern marine sediments.

2003: Characterization of the structure and the surface reactivity of a marcasite thin film

by Martin Schoonen

Elsetinow, A.R., Strongin, D.R., Borda, M.J., Schoonen, M.A.A., Rosso, K.M., 2003. Characterization of the structure and the surface reactivity of a marcasite thin film for surface science studies. Geochimica Cosmochimica Acta, 67: 807-812.

Synthesis of multiwalled carbon nanotubes from bamboo charcoal and the roles of minerals on their growth

by Jiangtao Zhu

Sorption of iodine on minerals investigated by X-ray absorption near edge structure (XANES) and 125I tracer sorption experiments

by Martin Schoonen

Fuhrmann, M., Bajt, S., Schoonen, M.A.A., 1998. Sorption of iodine on minerals investigated by X-ray absorption near edge structure (XANES) and 125I tracer sorption experiments. Applied Geochemistry, 13(2): 127-141.

Evaluating the use of 3'-(p-Aminophenyl) fluorescein for determining the formation of highly reactive oxygen species in particle suspensions

by Martin Schoonen

Corey A Cohn, Christopher E Pedigo, Shavonne N Hylton, Sanford R Simon, Martin AA Schoonen Geochemical Transactions 2009, 10:8 (11 August 2009) doi:10.1186/1467-4866-10-8

Background

Given the importance of highly reactive oxygen species (hROS) as reactants in a wide range of... more Background

Given the importance of highly reactive oxygen species (hROS) as reactants in a wide range of biological, photochemical, and environmental systems there is an interest in detection and quantification of these species. The extreme reactivity of the hROS, which includes hydroxyl radicals, presents an analytical challenge. 3'-(p-Aminophenyl) fluorescein (APF) is a relatively new probe used for measuring hROS. Here, we further evaluate the use of APF as a method for the detection of hydroxyl radicals in particle suspensions.
Results

Particle-generated hROS can be quantified with an estimated detection limit of 50 nM. Measurements of hROS in two National Institute of Standards and Technology (NIST 2709 and 2710) soil suspensions and a pyrite suspension show non-linear particle dose-response curves for hROS generation. APF can also be used in solutions containing no dissolved molecular oxygen (O2) to determine the role of O2 in the formation of hROS. Results confirm that O2 is mechanistically important in the formation of hROS by dissolved ferrous iron and in pyrite suspensions.
Conclusion

Given the non-linear dose-response curves for particle generation of hROS, we recommend using several particle loadings in experiments aimed to compare particles for their hROS generation potential. The method presented here is specific to hROS and simple to perform. The analysis can be conducted in mobile labs as only basic laboratory equipment is required.

Metal speciation and its role in bioaccessibility and bioavailability

by Martin Schoonen

Investigating Sorption on Iron-Oxyhydroxide Soil Minerals by Solid-State NMR Spectroscopy: A 6Li MAS NMR Study of Adsorption and Absorption on Goethite

by Martin Schoonen

Role of pyrite in formation of hydroxyl radicals in coal: possible implications for human health

by Martin Schoonen

Using yeast RNA as a probe for generation of hydroxyl radicals by earth materials

by Martin Schoonen

2007: Photodriven reduction and oxidation reactions on colloidal semiconductor particles: Implications for prebiotic synthesis

by Martin Schoonen

Zhang, X.V., Ellery, S.P., Friend, C.M., Holland, H.D., Michel, F.M., Schoonen, M.A.A., Martin, S.T., 2007. Photodriven reduction and oxidation reactions on colloidal semiconductor particles: Implications for prebiotic synthesis. Journal of Photochemistry and Photobiology a-Chemistry 185, 301-311.

A novel vertical attenuated total reflectance photochemical flow-through reaction cell for Fourier transform infrared spectroscopy

by Martin Schoonen

Borda, M.J., Strongin, D.R., Schoonen, M.A., 2003. A novel vertical attenuated total reflectance photochemical flow-through reaction cell for Fourier transform infrared spectroscopy. Spectrochimica Acta Part a-Molecular and Biomolecular Spectroscopy 59, 1103-1106.

A unique photochemical cell design and two experiments are presented, which illustrate the usefulness of flow-through... more A unique photochemical cell design and two experiments are presented, which illustrate the usefulness of flow-through attenuated total reflectance (ATR) Fourier transform infrared (FT-IR) spectroscopy as a technique for investigating photochemical reactions at the mineral-water interface. The kinetics of the photolysis reaction of potassium oxalate (K2C2O4) in a ferric iron solution and oxalate adsorbed onto goethite (α-FeOOH) were investigated to show the capabilities of the cell. Due to complicated kinetics, the adsorption experiment demonstrates not only the types of complex problems, that may exist at the mineral-water interface, but also the ability for this novel cell design to address them.

A perspective on the role of minerals in prebiotic synthesis

by Martin Schoonen

Nikolaus Boroffka, Gerhard Heck, Resursele minerale din România şi stadiul actual al cercetărilor privind mineritul preistoric. Apulum 43.1, 2006, pp. 71-94.

by Nikolaus Boroffka

Discussion of mineral resources (copper, tin, silver, gold, salt, amber) in Romania, and the (few) indications for... more Discussion of mineral resources (copper, tin, silver, gold, salt, amber) in Romania, and the (few) indications for their prehistoric exploitation, such as ancient mines, grooved hammers and prehistoric finds from mines. New IR-analyses for amber are presented and discussed.

Romanian version of a similar article in German (appeared 2009 - see above).

This volume of Apulum Journal is not yet online - the link is given, just in case you want to check again later.

Natural Medicine for Common Ailments

by Poppy Valentine

This is a collection of non-synthetic health tips for common illnesses. This is a collection of non-synthetic health tips for common illnesses.

Vitamini i minerali

by Boris Ilic

Co-authored

U ovome seminaru ukratko obradili smo neke od osnovnih stvari o
vitaminima i mineralima. Razlog zašto smo... more U ovome seminaru ukratko obradili smo neke od osnovnih stvari o
vitaminima i mineralima. Razlog zašto smo odabrali upravo ovu temu je naša želja da vas pa i sebe upoznamo s osnovnim važnostima vitamina i minerala. Obradili smo vitamine topive u vodi i mastima, specifičnosti svakih od njih te važnosti njihova postojanja. Isto smo napravili i sa mineralima od kojih smo izdvojili one za koje smo smatrali da su jedni od najvažnijih iako su svi oni podjednako važni za normalno funkcioniranje našeg organizma.