Skin debris	Skin elements				Mineral overload		Mineral and metallic particles at the surface
Numbers	Organic matter	Sulphur	Chlorine	Sodium	Clays	Calcium carbonate	Mineral and metallic particles at the surface
P1	+	+	+	+	+++	+	No
P2	+	+	+	?	++	+++	No
P3	+	+	+	+	+	+	Yes