| 1. |
- Aiglsperger, Thomas, et al.
(författare)
-
Fibrous Platinum-Group Minerals in “Floating Chromitites” from the Loma Larga Ni-Laterite Deposit, Dominican Republic
- 2016
-
Ingår i: Minerals. - Basel : MDPI. - 2075-163X. ; 6:4
-
Tidskriftsartikel (refereegranskat)abstract
- This contribution reports on the observation of enigmatic fibrous platinum-group minerals (PGM) found within a chromitite body included in limonite (“floating chromitite”) from Ni-laterites in the Dominican Republic. Fibrous PGM have a Ru-Os-Ir-Fe dominated composition and are characterized by fibrous textures explained by grain-forming fibers which are significantly longer (1–5 _m) than they are wide (~100 nm). Back-scattered electron (BSE) images suggest that these nanofibers are platinum-group elements (PGE)-bearing and form <5 _m thick layers of bundles which are oriented orthogonal to grains’ surfaces. Trace amounts of Si are most likely associated with PGE-bearing nanofibers. One characteristic fibrous PGM was studied in detail: XRD analyses point to ruthenian hexaferrum. However, the unpolished fibrous PGM shows numerous complex textures on its surface which are suggestive for neoformation processes: (i) features suggesting growth of PGE-bearing nanofibers; (ii) occurrence of PGM nanoparticles within film material (biofilm?) associated with PGE-bearing nanofibers; (iii) a Si-rich and crater-like texture hosting PGM nanoparticles and an Ir-rich accumulation of irregular shape; (iv) complex PGM nanoparticles with ragged morphologies, resembling sponge spicules and (v) oval forms (<1 _m in diameter) with included PGM nanoparticles, similar to those observed in experiments with PGE-reducing bacteria. Fibrous PGM found in the limonite may have formed due to supergene (bio-)weathering of fibrous Mg-silicates which were incorporated into desulphurized laurite during stages of serpentinization.
|
|
| 2. |
|
|
| 3. |
- Roqué Rosell, Josep, et al.
(författare)
-
Crystallographic information data of natural occurring zaccariniite (RhNiAs) obtained by means of precession electron diffraction
- 2019
-
Ingår i: Data in Brief. - : Elsevier. - 2352-3409. ; 25
-
Tidskriftsartikel (refereegranskat)abstract
- The crystal structure of naturally occurring zaccariniite (RhNiAs) has been studied in Transmission Electron Microscopy (TEM) with variable angle Precession Electron Diffraction (PED) techniques. The analysis of the data has yielded tetragonal cell parameters of 3.86, 3.86, 6.77 Å and space group of P4/nmm for the basic structure, and its constituent atom positions for Ni, As and Rh were determined as well by ab-initio structure resolution method. The data is related to “Structural characterization and ab-initio resolution of natural occurring zaccariniite (RhNiAs) by means of Precession Electron Diffraction” (Roqué Rosell et al., 2019).
|
|
| 4. |
- Roqué Rosell, Josep, et al.
(författare)
-
Structural characterization and ab-initio resolution of natural occurring zaccariniite (RhNiAs) by means of Precession Electron Diffraction
- 2019
-
Ingår i: Microchemical journal (Print). - : Elsevier. - 0026-265X .- 1095-9149. ; 148, s. 130-140
-
Tidskriftsartikel (refereegranskat)abstract
- The crystal structure of naturally occurring zaccariniite from Loma Peguera (Republica Dominicana) has been studied in Transmission Electron Microscopy(TEM) with variable angle Precession Electron Diffraction (PED) techniques: 0.7° Precession Electron Diffraction Tomography (Precession EDT) for unit cell and Laue class sorting, 0.5° Scanning Precession Diffraction (SPED) for crystal orientation mapping and grain alignment, and high symmetry zone axis 1.2° to 2.2° Zone Axis High Angle Precession Electron Diffraction (ZA high angle PED) for Space Group assessment and supercell information gathering. The natural sample has been prepared into an electron thin lamella by means of Focused Ion Beam(FIB). The analysis of the data has yielded tetragonal cell parameters of 3.86, 3.86, 6.77 Å and space group of P4/nmm for the basic structure, and its constituent atom positions for Ni, As and Rh were determined as well by ab-initio structure resolution method in accordance to the elemental composition of the natural zaccariniite obtained with Energy Dispersive X-ray (EDX) and High Magnification Electron Microscopy (HMEM) analysis. A modulation of the crystal basic structure of 3 by 1 in the basal plane has been reported for the first time on natural occurring zaccariniite.
|
|
