Reference:
▪ Schlüter, J., Malcherek, T., Pohl, D., Schäfer, C. (2018): Vondechenite, a new hydrous calcium copper chloride hydroxide, from the Bellerberg, East-Eifel volcanic area, Germany. Neues Jahrbuch fur Mineralogie - Abhandlungen: Journal of Mineralogy and Geochemistry, 195, 79-86.
Abstract:
The mineral vondechenite (IMA 2016-065), Cu4CaCl2(OH)8·4H2O, is a blue hydrous calcium copper chloride hydroxide with a new structure type. The translucent mineral has a vitreous lustre, exhibits a pale blue streak and shows a distinct pleochroism. Its crystals form tiny aggregates of platy crystals not exceeding 1 mm in diameter. Isolated imperfect tabular crystals with {010} as the dominant form are smaller. They have a diameter of not more than 0.5 mm and a thickness of less than 25 μm. Vondechenite is not fluorescent and shows a good cleavage on (010). The name vondechenite is for Ernst Heinrich von Dechen a scientific pioneer for the geology of the western part of Germany. Vondechenite is orthorhombic with space group symmetry Cmcm. Cu atoms are arranged in layers with a pseudo-square topology. Ca atoms are disordered with 48 % vacancies, but streaks of diffuse scattering parallel b* might indicate ordered layers of Ca atoms, with no long range order in b* direction. Unit cell parameters determined by X-ray single crystal diffraction are a = 6.653(1) Å, b = 15.034(3) Å, c = 6.611(1) Å, V = 661.3 (2) Å 3 and Z = 2. The calculated density is 2.85 g/cm3. The strongest lines observed in the simulated X-ray powder diffraction pattern are [d in Å/Irel in %] 7.60/100; 2.48/58; 2.52/49; 3.07/39; 1.73/39. Electron microprobe analyses gave (wt.%) CaO 10.44, CuO 58.25, Fe 0.33, Cl 13.31, O = Cl –3.01, H2 Ocalc. 25.14, sum 104.44 wt.% leading to an empirical formula of Ca1.01(Cu3.97Fe0.02)Cl2.03(OH)7.97·3.58H2O based on 5 cations pfu. The simplified formula is Cu4CaCl2(OH)8·4H2O which requires CaO 9.78, CuO 55.50, Cl 12.37 (O ≡ Cl –2.79), H2O 25.14, total 100.00 wt.%. The new mineral was collected in 1993 in the northern part of the Caspar quarry, Bellerberg volcano, East-Eifel volcanic area, Rhineland-Palatinate, Germany. Vondechenite was found in a xenolith of the Bellerberg basalt in a matrix of white ettringite and jennite.
▪ Schlüter, J., Malcherek, T., Pohl, D., Schäfer, C. (2018): Vondechenite, a new hydrous calcium copper chloride hydroxide, from the Bellerberg, East-Eifel volcanic area, Germany. Neues Jahrbuch fur Mineralogie - Abhandlungen: Journal of Mineralogy and Geochemistry, 195, 79-86.
Abstract:
The mineral vondechenite (IMA 2016-065), Cu4CaCl2(OH)8·4H2O, is a blue hydrous calcium copper chloride hydroxide with a new structure type. The translucent mineral has a vitreous lustre, exhibits a pale blue streak and shows a distinct pleochroism. Its crystals form tiny aggregates of platy crystals not exceeding 1 mm in diameter. Isolated imperfect tabular crystals with {010} as the dominant form are smaller. They have a diameter of not more than 0.5 mm and a thickness of less than 25 μm. Vondechenite is not fluorescent and shows a good cleavage on (010). The name vondechenite is for Ernst Heinrich von Dechen a scientific pioneer for the geology of the western part of Germany. Vondechenite is orthorhombic with space group symmetry Cmcm. Cu atoms are arranged in layers with a pseudo-square topology. Ca atoms are disordered with 48 % vacancies, but streaks of diffuse scattering parallel b* might indicate ordered layers of Ca atoms, with no long range order in b* direction. Unit cell parameters determined by X-ray single crystal diffraction are a = 6.653(1) Å, b = 15.034(3) Å, c = 6.611(1) Å, V = 661.3 (2) Å 3 and Z = 2. The calculated density is 2.85 g/cm3. The strongest lines observed in the simulated X-ray powder diffraction pattern are [d in Å/Irel in %] 7.60/100; 2.48/58; 2.52/49; 3.07/39; 1.73/39. Electron microprobe analyses gave (wt.%) CaO 10.44, CuO 58.25, Fe 0.33, Cl 13.31, O = Cl –3.01, H2 Ocalc. 25.14, sum 104.44 wt.% leading to an empirical formula of Ca1.01(Cu3.97Fe0.02)Cl2.03(OH)7.97·3.58H2O based on 5 cations pfu. The simplified formula is Cu4CaCl2(OH)8·4H2O which requires CaO 9.78, CuO 55.50, Cl 12.37 (O ≡ Cl –2.79), H2O 25.14, total 100.00 wt.%. The new mineral was collected in 1993 in the northern part of the Caspar quarry, Bellerberg volcano, East-Eifel volcanic area, Rhineland-Palatinate, Germany. Vondechenite was found in a xenolith of the Bellerberg basalt in a matrix of white ettringite and jennite.