TY - JOUR
T1 - A Modern, Guano-Related Occurrence of Foggite, CaAl(POsub4/sub)(OH)sub2/sub·Hsub2/subO and Churchite-(Y), YPOsub4/sub·2Hsub2/subO in Cioclovina Cave, Romania
AU - Onac, Bogdan P.
AU - Ettinger, K.
AU - Kearns, Joe B
AU - Balasz, I. I.
PY - 2005/12/1
Y1 - 2005/12/1
N2 - This study reports foggite and churchite-(Y) from two spatially separate locations in the guano-related phosphate deposit from the Cioclovina Cave, Romania. Optical microscope observations, powder X-ray diffraction, electron microprobe analyses, and FTIR were used in the analysis of the two minerals. The chemical composition of foggite was determined to be Ca 0.925 (Al 0.91 Fe 2+ 0.016 ) Σ0.926 (P 0.991 Si 0.043 ) Σ1.034 O 3.74 (OH) 2.26 · H 2 O and churchite-(Y) [(Y 0.830 Dy 0.043 Er 0.033 Gd 0.029 Yb 0.022 ) Σ0.957 Ca 0.009 ]P 1.023 O 4.00 · 2H 2 O. Chemical analyses of Cioclovina churchite-(Y) clearly revealed enrichment in lanthanides of even atomic number. The refined unit-cell parameters are for foggite (orthorhombic) a = 9.264(1) Å, b = 21.334(8) Å, c = 5.197(7) Å, and V = 1027.13(8) Å 3 ( Z = 8); for churchite-(Y) (monoclinic): a = 5.578(8) Å, b = 15.013(6) Å, c = 6.277(8) Å, β = 117.94(4)°, and V = 464.38(5) Å 3 ( Z = 4). FTIR spectrum of churchite-(Y) exhibits all the bands assigned to the vibrations of PO 4 , OH, and water groups. Unlike other documented occurrences of foggite and churchite-(Y), in Cioclovina Cave, the occurrence of these minerals are related to a process that phosphatized subjacent limestone and various cave sediments (sand, clay, and limy mud) to form a complex phosphate assemblage. The minerals are presumably derived from phosphate-rich solutions that reacted with clay earth while moving downward through the sediments. Foggite was formed at the expense of the originally precipitated crandallite. Locally concentrated yttrium, REE, and dissolved phosphate are probably responsible for the precipitation of churchite-(Y).
AB - This study reports foggite and churchite-(Y) from two spatially separate locations in the guano-related phosphate deposit from the Cioclovina Cave, Romania. Optical microscope observations, powder X-ray diffraction, electron microprobe analyses, and FTIR were used in the analysis of the two minerals. The chemical composition of foggite was determined to be Ca 0.925 (Al 0.91 Fe 2+ 0.016 ) Σ0.926 (P 0.991 Si 0.043 ) Σ1.034 O 3.74 (OH) 2.26 · H 2 O and churchite-(Y) [(Y 0.830 Dy 0.043 Er 0.033 Gd 0.029 Yb 0.022 ) Σ0.957 Ca 0.009 ]P 1.023 O 4.00 · 2H 2 O. Chemical analyses of Cioclovina churchite-(Y) clearly revealed enrichment in lanthanides of even atomic number. The refined unit-cell parameters are for foggite (orthorhombic) a = 9.264(1) Å, b = 21.334(8) Å, c = 5.197(7) Å, and V = 1027.13(8) Å 3 ( Z = 8); for churchite-(Y) (monoclinic): a = 5.578(8) Å, b = 15.013(6) Å, c = 6.277(8) Å, β = 117.94(4)°, and V = 464.38(5) Å 3 ( Z = 4). FTIR spectrum of churchite-(Y) exhibits all the bands assigned to the vibrations of PO 4 , OH, and water groups. Unlike other documented occurrences of foggite and churchite-(Y), in Cioclovina Cave, the occurrence of these minerals are related to a process that phosphatized subjacent limestone and various cave sediments (sand, clay, and limy mud) to form a complex phosphate assemblage. The minerals are presumably derived from phosphate-rich solutions that reacted with clay earth while moving downward through the sediments. Foggite was formed at the expense of the originally precipitated crandallite. Locally concentrated yttrium, REE, and dissolved phosphate are probably responsible for the precipitation of churchite-(Y).
KW - Clay
KW - Yttrium
KW - Atomic Number
KW - Romania
KW - Electron Microprobe
UR - https://digitalcommons.usf.edu/gly_facpub/107
UR - https://doi.org/10.1007/s00710-005-0106-4
U2 - 10.1007/s00710-005-0106-4
DO - 10.1007/s00710-005-0106-4
M3 - Article
VL - 85
JO - Mineralogy and Petrology
JF - Mineralogy and Petrology
ER -