Rezumat articol ediţie STUDIA UNIVERSITATIS BABE┼×-BOLYAI

În partea de jos este prezentat rezumatul articolului selectat. Pentru revenire la cuprinsul ediţiei din care face parte acest articol, se accesează linkul din titlu. Pentru vizualizarea tuturor articolelor din arhivă la care este autor/coautor unul din autorii de mai jos, se accesează linkul din numele autorului.

 
       
         
    STUDIA GEOLOGIA - Ediţia nr.1 din 2004  
         
  Articol:   VARISCITE (ALPO4Ľ2H2O) FROM CIOCLOVINA CAVE (ŞUREANU MOUNTAINS, ROMANIA): A TALE OF A MISSING PHOSPHATE.

Autori:  BOGDAN P. ONAC, J. KEARNS, RADU C. BREBAN, SIMONA CINT─é P├éNZARU.
 
       
         
  Rezumat:  Recent investigations on a phosphatized sediment sequence in the Cioclovina Cave led to the identification of a second occurrence in Romania (first time in the cave environment) of variscite, AlPO4Ľ2H2O. The mineral exists as dull-white, tiny crusts and veinlets within the thick argillaceous material accumulated on the cave floor. Under scanning electron microscope (SEM) variscite appears as subhedral to euhedral micron-size crystals. The {111} pseudo-octahedral form is rather common. Variscite was further characterized by means of X-ray diffraction, thermal, vibrational FT-IR and FT-Raman spectroscopy, and by SEM energy-dispersive spectrometry (EDS). The calculated orthorhombic cell parameters are a = 9.823(4), b = 8.562(9), c = 9.620(5) ┼, and V = 809.167(6) ┼3. The ED spectrum of variscite shows well-resolved Al and P lines confirming thus the presence of the major elements in our compound. The formation of variscite is attributed to the reaction between the phosphate-rich leachates derived from guano and the underlying clay sediments.  
         
     
         
         
      Revenire la pagina precedentă