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- Hålenius, Ulf, et al.
(author)
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Mangani-pargasite, NaCa2(Mg4Mn3+)(Si6Al2)O22(OH)2, a new mineral species of the amphibole supergroup
- 2020
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In: Periodico di Mineralogia. - : EDIZIONI NUOVA CULTURA. - 0369-8963 .- 2239-1002. ; 89:2, s. 125-131
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Journal article (peer-reviewed)abstract
- Mangani-pargasite, ideally NaCa2(Mg4Mn3+)(Si6Al2)O-22(OH)(2), is a new mineral species of the calcium amphibole subgroup of the amphibole supergroup. The type specimen was found on the mine dump of the Langban Fe-Mn-(Ba-As-Pb-Sb) deposit in Varmland, Sweden. Crystal chemical analyses resulted in the empirical chemical formula: (A)(Na0.90Pb0.07K0.03)(Sigma 1.00)(B)(Ca1.93Mn0.072+)(Sigma 2.00)(C)(Mg4.25Mn0.393+Al0.26Fe0.103+)Sigma(T)(5.00)(Si6.35Al1.65)Sigma 8.00O22W(OH)(2). In order to complete the description of this newly approved (IMA 2018-151) mineral we report here additional data to those published in papers by Jonsson and Halenius (2010) and Halenius and Bosi (2012). Mangani-pargasite is biaxial positive, with alpha=1.635(5), beta=1.645(5), gamma=1.660(5) and the measured optic angle 2V is 85(5)degrees. The dispersion is weak (r>v), and the optic orientation is: Y parallel to b; Z<^>c=25(3)degrees. Mangani-pargasite is red to brownish red with weak pleochroism; X=pale reddish brown, Y=pale reddish brown and Z=pale brownish red; X approximate to Y>Z. The unit-cell parameters are a=9.9448(5), b=18.0171(9), c=5.2829(3) angstrom, beta=105.445(3)degrees, V=912.39(9) angstrom(3), Z=2, space group C2/m. The ten strongest reflections in the X-ray powder diffraction pattern [d-values in angstrom, I, (h k l)] are: 8.420, 29, (110); 3.368, 17, (131), 3.279, 49, (240); 3.141, 100, (310); 2.817, 44, (33 0); 2.698, 21, (151); 2.389, 18, (350); 1.904, 29, (510); 1.650, 22, (461) and 1.448, 46, (661).
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- Oudbashi, Omid, 1978, et al.
(author)
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Chemical and microstructural analysis of some Achaemenian silver alloy artefacts from Hamedan, western Iran
- 2015
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In: Periodico di Mineralogia. - 0369-8963 .- 2239-1002. ; 84:3A, s. 419-434
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Journal article (peer-reviewed)abstract
- Precious metals have been often employed to manufacture various decorative artefacts at Pre-Islamic Iran. One of the most outstanding phenomena from this period of Iran was the extraordinary occurrence of the silver application to make various decorative objects. Indeed, application of silver and its alloys was extended for making different vessels and other decorative and royal objects in historic time, especially in Achaemenid (550-330 BC) and Sasanian (224-642 AD) Empires. In this paper, four silver artefacts dated to Achaemenid period, found in Hamedan region, Western Iran, are investigated to identify manufacturing/shaping process as well as alloy composition. The examined objects consist of two bowls, one decorated plate and one decorated spoon with the head of a felidae. Scanning Electron Microscopy-Energy Dispersive X-ray Spectrometry (SEM-EDS) method has been applied on cross section samples to determine chemical composition of the alloys and the phases and optical microscopy (Metallography) and SEM techniques were used to study of microstructure and manufacturing/shaping procedure. The results showed that all samples were made of silver-copper alloys with different amount of copper in each artefact. Other elements have detected in minor/trace contents such as As, Pb, Cd, Al, S. The microstructure of samples showed interesting features that are related to manufacturing/shaping process to make silver artefacts and compositional aspects of the objects because of copper amount. In fact, two-phased microstructure could be observed in two Achaemenian silver bowls because of the high amount of copper in alloy composition. Two other artefacts include single phase microstructure depending on low content of copper in alloy composition.
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| 4. |
- Di Maio, Giovanni, et al.
(author)
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Mineralogical and geochemical characterization of the concotto artefacts from firing places of Longola protohistoric settlement (Naples)
- 2011
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In: Periodico di Mineralogia. - 0369-8963. ; 80:3, s. 351-367
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Journal article (peer-reviewed)abstract
- A set of concotto samples, a type of fired mixture of various raw materials, coming from firing place of the perifiuvial protohistoric site of Longola (Campania region, southern Italy) was characterized by means of a multi-analytical approach, i.e. polarized light optical microscopy (OM), X-ray powder diffraction (XRD), scanning electron microscopy and energy dispersive spectrometry (SEM-EDS), X-ray fluorescence (XRF), inductively-coupled plasma-mass spectrometry (ICP-MS) and Mossbauer spectroscopy. The specimens generally show a heterogeneous texture, a red-coloured groundmass composed of a mixture of tiny quartz, feldspar, poorly-crystallized goethite, hematite and clay minerals. The crystal fractions show significant amounts of quartz and alkali feldspar and variable percentages of clinopyroxene, leucite, biotite, hematite, magnetite and traces of muscovite. Random secondary phases of calcite, vivianite and gypsum have been identified. The coarser fraction is formed by several types of inclusions, i.e. tephra fragments (pumices, scoriae), volcanic and sedimentary rocks. Illite and very subordinate smectite (montmorillonite) were detected by X-ray diffraction. Trace elements also show a contribution of volcanic raw materials. The Mossbauer analyses at 296 K show the occurrence of paramagnetic Fe(3+) iron (clay minerals) and magnetic Fe(3+) iron (hematite). For the 80 K spectrum, however, two doublets (ferrous and ferric iron in clay minerals) and one sextet (hematite). The concotto samples do not suffer high temperatures, perhaps much lower than 500-600 degrees C in a mainly oxidizing atmosphere. Only sporadically, if any, higher temperatures (> 800 degrees C) might have been reached.
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