Fig. 7
Polarized optical microscopy (POM) photographs of selected ceramic samples: a general view of a reddish matrix in which angular quartz grains grey coloured can be recognized. Note the orientation of phyllosilicates in the matrix; b incipient argillification of K-feldspar grain; c presence of an isolated biotite grain with speckled extinction; d amphibole with first order yellow interference colour observed in the sample CNDI 04; e small epidote s.s. grains with red to blue interference colours observed in the sample CNDI 11; f isolated zircon crystal in CNDI 08 in the centre of the image with high interference colour; g presence of quartz grains with angular morphology and undulose extinction in a black core in sample CNDI 06; h development of a thin red level composed of Fe oxides in CNDI 12