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Fig. 6 Natural cleft porphyry. Grigio misto (mixed grey). Grigio misto is never uniform. Its dominant hues are grey, purple-grey and light brown. Obviously, colour intensity varies based on type. Patagonian porphyry (Argentina), for example, has a grey background colour with whitish-pink specks, while a variety ofTrentino porphyry (Italy) always features a spotted grey background specked with pink and black.

Fig. 7 Natural cleft porphyry. Rossiccio misto (mixed reddish). Dominant shading is red, pink, red-dish, dark ochre. Specks in the background colour are pink,whitish and dark grey. Sometimes rust-coloured spots are visible,which will altering the dominant hue in a given area. This category includes mixed Patagonian porphyry and all multi-coloured pieces with a predominant red hue and slightly rough natural cleft surface.