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- Title
Calcinaksite, KNaCa(SiO) HO, a new mineral from the Eifel volcanic area, Germany.
- Authors
Chukanov, Nikita; Aksenov, Sergey; Rastsvetaeva, Ramiza; Blass, Günter; Varlamov, Dmitry; Pekov, Igor; Belakovskiy, Dmitry; Gurzhiy, Vladislav
- Abstract
The new mineral calcinaksite, ideally KNaCa(SiO) · HO, the first hydrous and Ca-dominant member of the litidionite group, is found in a xenolith of metamorphosed carbonate-rich rock from the southern lava flow of the Bellerberg volcano, Eastern Eifel region, Rheinland-Pfalz, Germany. It is associated with wollastonite, gehlenite, brownmillerite, CaSiO (larnite or calcio-olivine), quartz, aragonite, calcite, jennite, tobermorite and ettringite. Calcinaksite occurs as clusters of colourless to light-grey subhedral prismatic crystals. The mineral is brittle, with Mohs' hardness of 5; D is 2.62(2) g/cm and D is 2.623 g/cm. The IR spectrum shows the presence of HO molecules forming three different H-bonds. Calcinaksite is optically biaxial (+), α = 1.542(2), β = 1.550(2), γ = 1.565(3), 2 V = 75(10). The chemical composition (electron-microprobe data, HO determined by the Alimarin method, wt%) is: NaO 6.69, KO 12.01, CaO 15.04, FeO 0.59, SiO 61.46, HO 4.9, total 100.69. The empirical formula is H KNaCaFeSiO. The crystal structure was solved and refined to R = 0.053, wR = 0.075 based upon 3057 reflections having I > 3σ( I). Calcinaksite is triclinic, space group P $$ \overline{1} $$ a = 7.021(2), b = 8.250(3), c = 10.145(2) Å. α = 102.23(2)°, β = 100.34(2)°, γ = 115.09(3)°, V = 495.4(3) Å, Z = 2. The strongest reflections of the X-ray powder pattern [ d, Å ( I,%) ( hkl)] are: 3.431 (70) (−121, −211, −210, 012, 0-22), 3.300 (67) (−031), 3.173 (95) (−103, −201, −220, 003, 111), 3.060 (100) (−212, 2-11, −221, 200, −1-13, 021, −202), 2.851 (83) (0-23, −122, 1-13, 1-31), 2.664 (62) (1-23, −222, 201).
- Subjects
GERMANY; POTASSIUM compounds; VOLCANOES; CALCIUM; CARBONATE minerals; HYDROGEN bonding
- Publication
Mineralogy & Petrology, 2015, Vol 109, Issue 4, p397
- ISSN
0930-0708
- Publication type
Academic Journal
- DOI
10.1007/s00710-015-0376-4