A new microenvironment for the formation of clay minerals: the example of authigenic halloysite-7Å and gibbsite in a stalactite from Agios Georgios Cave, Kilkis, north Greece, Elena Ifandi, Basilios Tsikouras, Dimitrios Papoulis, Konstantin Hatzipanagiotou, Aspasia Antonelou
International Journal of Speleology