SEARCH Articles Figures Tables X -ray diffraction patterns of the CaCC 3 halloysite composite after CaC03 formation. The first peak at 12.3 corresponds to 7.2 A . Arrows indicate peaks corresponding to the vaterite modification of CaC03. Calcite modification of CaC03 was not found. Peak assignment was made using the Powder Diffraction Database. [Publishers Imprint]