First occurrence of close-to-ideal Kirkiite at Vulcano (Aeolian Islands, Italy): Chemical data and single- crystal X-ray study
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First occurrence of close-to-ideal Kirkiite at Vulcano (Aeolian Islands, Italy) : Chemical data and single- crystal X-ray study. / Pinto, Daniela; Balic-Zunic, Tonci; Garavelli, anna; Garbarino, Carlo; Makovicky, Emil; Vurro, Filippo.
I: European Journal of Mineralogy, Bind 18, Nr. 3, 2006, s. 393-401.Publikation: Bidrag til tidsskrift › Tidsskriftartikel › Forskning › fagfællebedømt
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TY - JOUR
T1 - First occurrence of close-to-ideal Kirkiite at Vulcano (Aeolian Islands, Italy)
T2 - Chemical data and single- crystal X-ray study
AU - Pinto, Daniela
AU - Balic-Zunic, Tonci
AU - Garavelli, anna
AU - Garbarino, Carlo
AU - Makovicky, Emil
AU - Vurro, Filippo
PY - 2006
Y1 - 2006
N2 - Samples of kirkiite from the high temperature fumaroles of La Fossa crater of Vulcano (Aeolian islands, Italy) were chemically and structurally investigated in this work. Associated minerals are vurroite, bismuthinite, galenobismutite, cannizzarite, lillianite, heyrovskite, galena, and other less characterized Pb(Bi)-sulfochlorides. Electron-microprobe analyses gave the average chemical formula Pb10.00Bi3.01As3.01(S18.47Se0.44C10.06) which is very close to the ideal composition of kirkiite, Pb10Bi3As3S19, and indeed significantly closer than the composition of the type specimen, Pb10.08Bi2.55Sb0.13As2.91S19. Lattice parameters are: a = 8.700(2) Å, ß = 26.237(6) Å, c = 8.774(3) Å, ß = 119.653(4)°, V = 1740.2(9) Å3. A twinned structure was refined using single-crystal data (MoK X-ray diffraction, CCD detector). The refinement converges to R = 0.074 for 1443 reflections with F0 > 4(F0). The structure of the close-to-ideal kirkiite from Vulcano has been compared with the structure of the type specimen. The comparison reveals a variation in As-Bi substitution, with samples from Vulcano probably being close to the maximum possible Bi and the minimum As content for this structure type. This is reflected in more regular and symmetric coordination polyhedra than in the holotype, as well as in the overall regularity of the structure. The increased Bi:As ratio produces an elongation of the a and b lattice periods, and a shortening of the c period, and increases the frequency of twinning in kirkiite.
AB - Samples of kirkiite from the high temperature fumaroles of La Fossa crater of Vulcano (Aeolian islands, Italy) were chemically and structurally investigated in this work. Associated minerals are vurroite, bismuthinite, galenobismutite, cannizzarite, lillianite, heyrovskite, galena, and other less characterized Pb(Bi)-sulfochlorides. Electron-microprobe analyses gave the average chemical formula Pb10.00Bi3.01As3.01(S18.47Se0.44C10.06) which is very close to the ideal composition of kirkiite, Pb10Bi3As3S19, and indeed significantly closer than the composition of the type specimen, Pb10.08Bi2.55Sb0.13As2.91S19. Lattice parameters are: a = 8.700(2) Å, ß = 26.237(6) Å, c = 8.774(3) Å, ß = 119.653(4)°, V = 1740.2(9) Å3. A twinned structure was refined using single-crystal data (MoK X-ray diffraction, CCD detector). The refinement converges to R = 0.074 for 1443 reflections with F0 > 4(F0). The structure of the close-to-ideal kirkiite from Vulcano has been compared with the structure of the type specimen. The comparison reveals a variation in As-Bi substitution, with samples from Vulcano probably being close to the maximum possible Bi and the minimum As content for this structure type. This is reflected in more regular and symmetric coordination polyhedra than in the holotype, as well as in the overall regularity of the structure. The increased Bi:As ratio produces an elongation of the a and b lattice periods, and a shortening of the c period, and increases the frequency of twinning in kirkiite.
KW - Faculty of Science
KW - Kirkiite
KW - krystal strukturer
KW - sulfosalte
KW - kirkiite
KW - Vulcano fumaroles
KW - twinning
KW - crystal structure
KW - sulfosalts
U2 - 1221/2006/0018-0393
DO - 1221/2006/0018-0393
M3 - Journal article
VL - 18
SP - 393
EP - 401
JO - European Journal of Mineralogy
JF - European Journal of Mineralogy
SN - 0935-1221
IS - 3
ER -
ID: 80383