Figure 4
ESEM images obtained on the outer surface of the studied samples, (a): green pigment, bright grey crystals of cuprorivaite are observed (1000×, scale bar = 50 μm), (b) iron oxides are observed in the green pigment sample (2000×, scale bar = 20 μm), (c) red pigment sample and the fine grains of haematite are observed (2000×, scale bar = 20 μm ), (d) yellow pigment, fine grained goethite are observed and carbon black are centred in the image (650×, scale bar = 100 μm), (e) black pigment, the fibrous structure of a vegetable matter can be observed (800×, scale bar = 50 μm) and (f) the plaster sample (2000×, scale bar = 20 μm).