The STUDIA UNIVERSITATIS BABEÅž-BOLYAI issue article summary

The summary of the selected article appears at the bottom of the page. In order to get back to the contents of the issue this article belongs to you have to access the link from the title. In order to see all the articles of the archive which have as author/co-author one of the authors mentioned below, you have to access the link from the author's name.

  
       
         
    STUDIA GEOLOGIA - Issue no. 1 / 2004  
         
  Article:   VARISCITE (ALPO4•2H2O) FROM CIOCLOVINA CAVE (ŞUREANU MOUNTAINS, ROMANIA): A TALE OF A MISSING PHOSPHATE.

Authors:  BOGDAN P. ONAC, J. KEARNS, RADU C. BREBAN, SIMONA CINTÄ‚ PÂNZARU. 		 
       
         
  Abstract:  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, AlPO4•2H2O. 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) Å, and V = 809.167(6) Å3. 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.  
         
     
         
         
      Back to previous page