Publication Date:
2018
Description:
〈div data-abstract-type="normal"〉〈p〉The new mineral fluorarrojadite-(BaNa), ideally BaNa〈span〉4〈/span〉CaFe〈span〉13〈/span〉Al(PO〈span〉4〈/span〉)〈span〉11〈/span〉(PO〈span〉3〈/span〉OH)F〈span〉2〈/span〉 was found on the dump of Elisabeth adit near Gemerská Poloma, Slovakia. It occurs in hydrothermal quartz veins intersecting highly fractionated, topaz–zinnwaldite S-type leucogranite. Fluorarrojadite-(BaNa) is associated with fluorapatite, ‘fluordickinsonite-(BaNa)’, triplite, viitaniemiite and minor amounts of other minerals. It forms fine-grained irregular aggregates up to 4 cm x 2 cm, which consist of individual anhedral grains up to 0.01 mm in size. It has a yellowish-brown to greenish-yellow colour, very pale yellow streak and a vitreous to greasy lustre. Mohs hardness is ~4½ to 5. The fracture is irregular and the tenacity is brittle. The measured density is 3.61(2) g cm〈span〉–3〈/span〉 and calculated density is 3.650 g cm〈span〉–3〈/span〉. Fluorarrojadite-(BaNa) is biaxial (+) and nonpleochroic. The calculated refractive index based on empirical formula is 1.674. The empirical formula (based on 47 O and 3 (OH + F) apfu) is 〈span〉A1〈/span〉(Ba〈span〉0.65〈/span〉K〈span〉0.35〈/span〉)〈span〉Σ1.00〈/span〉 〈span〉A2〈/span〉Na〈span〉0.35〈/span〉 〈span〉B1〈/span〉(Na〈span〉0.54〈/span〉Fe〈span〉0.46〈/span〉)〈span〉Σ1.00〈/span〉 〈span〉B2〈/span〉Na〈span〉0.54〈/span〉〈span〉Ca〈/span〉(Ca〈span〉0.74〈/span〉Sr〈span〉0.20〈/span〉Pb〈span〉0.02〈/span〉Ba〈span〉0.04〈/span〉)〈span〉Σ1.00〈/span〉Na〈span〉2〈/span〉 〈span〉Na3〈/span〉Na〈span〉0.46〈/span〉 〈span〉M〈/span〉(Fe〈span〉7.16〈/span〉Mn〈span〉5.17〈/span〉Li〈span〉0.37〈/span〉Mg〈span〉0.12〈/span〉Sc〈span〉0.08〈/span〉Zn〈span〉0.06〈/span〉Ga〈span〉0.02〈/span〉Ti〈span〉0.02〈/span〉)〈span〉Σ13.00〈/span〉 Al〈span〉1.02〈/span〉P〈span〉11〈/span〉O〈span〉44〈/span〉PO〈span〉3.46〈/span〉(OH)〈span〉0.54〈/span〉 〈span〉W〈/span〉(F〈span〉1.54〈/span〉OH〈span〉0.46〈/span〉). Fluorarrojadite-(BaNa) is monoclinic, space group 〈span〉Cc〈/span〉, 〈span〉a〈/span〉 = 16.563(1) Å, 〈span〉b〈/span〉 = 10.0476(6) Å, 〈span〉c〈/span〉 = 24.669(1) Å, β = 105.452(4)°, 〈span〉V〈/span〉 = 3957.5(4) Å〈span〉3〈/span〉 and 〈span〉Z〈/span〉 = 4. The seven strongest reflections in the powder X-ray diffraction pattern are [〈span〉d〈/span〉〈span〉obs〈/span〉 in Å, (I), 〈span〉hkl〈/span〉]: 3.412, (21), 116; 3.224, (37), 206; 3.040, (100), 42〈span〉〈span〉〈img data-mimesubtype="gif" data-type="simple" src="http://static.cambridge.org/resource/id/urn:cambridge.org:id:binary:20181017132303927-0397:S0026461X18000166:S0026461X18000166_inline1.gif"〉
〈span data-mathjax-type="texmath"〉
〈/span〉
〈/span〉〈/span〉; 2.8499, (22), 33〈span〉〈span〉〈img data-mimesubtype="gif" data-type="simple" src="http://static.cambridge.org/resource/id/urn:cambridge.org:id:binary:20181017132303927-0397:S0026461X18000166:S0026461X18000166_inline2.gif"〉
〈span data-mathjax-type="texmath"〉
〈/span〉
〈/span〉〈/span〉; 2.7135, (56), 226; 2.5563, (33), 028 and 424; 2.5117, (23), 040. The new mineral is named according to the nomenclature scheme of arrojadite-group minerals, approved by the IMA CNMNC. In fluorarrojadite-(BaNa), Fe〈span〉2+〈/span〉 is a dominant cation at the 〈span〉M〈/span〉 site (so the root-name is arrojadite) and two suffixes are added to the root-name according to the dominant cation of the dominant valence state at the 〈span〉A〈/span〉1 (Ba〈span〉2+〈/span〉) and 〈span〉B〈/span〉1 sites (Na〈span〉+〈/span〉). A prefix fluor is added to the root-name as F〈span〉–〈/span〉 is dominant over (OH)〈span〉–〈/span〉 at the 〈span〉W〈/span〉 site.〈/p〉〈/div〉
Print ISSN:
0026-461X
Electronic ISSN:
1471-8022
Topics:
Geosciences
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