Table 2. Main characteristics of clay minerals and clay mixtures.

Table 2. Main characteristics of clay minerals and clay mixtures.

	Type	Site	Shape	Pleochroism	Color with crossed polars	Mode of occurrence	Where	Associated minerals	Dominant chemical feature	Mineral
1	Pale brown	1025, 1027, 1028, 1032	Fibers or cryptocrystalline granules	Nonexistent	Gray first order	M1-M4	GI	Carbonates, sulfides	High FeO_t, low MgO	Fe-rich saponite
2	Very pale green	1023, 1024, 1026, 1027, 1028,1029, 1031, 1032	Fibers or rare cryptocrystalline granules	Nonexistent	Gray first order to orange	M1-M4	TZ	Celadonite, Fe-rich saponite, iddingsite	High MgO, low FeO_t	Mg-rich saponite
3	Bright green	1029	Cryptocrystalline massive aggregates	Slight	Second order often masked by the green color	M1, M3, M4	GH, RH, TZ	Iddingsite, Mg-rich saponite, Fe-oxyhydroxides	High K₂O, medium FeO_t	Celadonite
4	Green	1023, 1024, 1026, 1027, 1028,1029, 1031, 1032	Fibers	Nonexistent	Masked by the color	M1-M4	GH, RH, TZ	Iddingsite, Mg-rich saponite, Fe-oxyhydroxides	Medium K₂O, medium FeO_t	Saponite-celadonite mixtures
5	Yellow green	1023, 1024, 1026, 1027, 1028,1029, 1031, 1032	Fibers	Nonexistent	Masked by the color	M1-M4	GH, RH, TZ	Iddingsite, Mg-rich saponite, Fe-oxyhydroxides	Medium K₂O, medium FeO_t	Saponite-celadonite or saponite-nontronite mixtures
6	Bright orange yellow	1023, 1024, 1026, 1027, 1028,1029, 1031, 1032	Fibers or cryptocrystalline granules	Nonexistent	Masked by the color	M1-M4	RH, GH	Iddingsite, Fe-oxyhydroxides	Medium K₂O, medium FeO_t	Iddingsite-celadonite mixtures
7	Orange to red	1023, 1024, 1026, 1027, 1028,1029, 1031, 1032	Cryptocrystalline granules	Nonexistent	Masked by the color	M1-M4	RH, GH	Iddingsite, Fe-oxyhydroxides	Low K₂O, high FeO_t	Iddingsite-celadonite mixtures
8	Dark brownish red	1023, 1024, 1026, 1027, 1028,1029, 1031, 1032	Massive cryptocrystalline aggregates	Nonexistent	Almost opaque	M1, M2	RH	Fe-oxyhydroxides, celadonite	Very high FeO_t, medium SiO₂	Iddingsite
9	Dark bright red	1023, 1024, 1026, 1027, 1028,1029, 1031, 1032	Massive cryptocrystalline aggregates	Nonexistent	Almost opaque	M1, M2	RH	Fe-oxyhydroxides, celadonite	Very high FeO_t, low SiO₂	Iddingsite

Type

Site

Shape

Pleochroism

Color with crossed polars

Mode of occurrence

Where

Associated minerals

Dominant chemical feature

Mineral

1 Pale brown 1025, 1027, 1028, 1032 Fibers or cryptocrystalline granules Nonexistent Gray first order M1-M4 GI Carbonates, sulfides High FeO_t, low MgO Fe-rich saponite

2 Very pale green 1023, 1024, 1026, 1027, 1028,1029, 1031, 1032 Fibers or rare cryptocrystalline granules Nonexistent Gray first order to orange M1-M4 TZ Celadonite, Fe-rich saponite, iddingsite High MgO, low FeO_t Mg-rich saponite

3 Bright green 1029 Cryptocrystalline massive aggregates Slight Second order often masked by the green color M1, M3, M4 GH, RH, TZ Iddingsite, Mg-rich saponite, Fe-oxyhydroxides High K₂O, medium FeO_t Celadonite

4 Green 1023, 1024, 1026, 1027, 1028,1029, 1031, 1032 Fibers Nonexistent Masked by the color M1-M4 GH, RH, TZ Iddingsite, Mg-rich saponite, Fe-oxyhydroxides Medium K₂O, medium FeO_t Saponite-celadonite mixtures

5 Yellow green 1023, 1024, 1026, 1027, 1028,1029, 1031, 1032 Fibers Nonexistent Masked by the color M1-M4 GH, RH, TZ Iddingsite, Mg-rich saponite, Fe-oxyhydroxides Medium K₂O, medium FeO_t Saponite-celadonite or saponite-nontronite mixtures

6 Bright orange yellow 1023, 1024, 1026, 1027, 1028,1029, 1031, 1032 Fibers or cryptocrystalline granules Nonexistent Masked by the color M1-M4 RH, GH Iddingsite, Fe-oxyhydroxides Medium K₂O, medium FeO_t Iddingsite-celadonite mixtures

7 Orange to red 1023, 1024, 1026, 1027, 1028,1029, 1031, 1032 Cryptocrystalline granules Nonexistent Masked by the color M1-M4 RH, GH Iddingsite, Fe-oxyhydroxides Low K₂O, high FeO_t Iddingsite-celadonite mixtures

8 Dark brownish red 1023, 1024, 1026, 1027, 1028,1029, 1031, 1032 Massive cryptocrystalline aggregates Nonexistent Almost opaque M1, M2 RH Fe-oxyhydroxides, celadonite Very high FeO_t, medium SiO₂ Iddingsite

9 Dark bright red 1023, 1024, 1026, 1027, 1028,1029, 1031, 1032 Massive cryptocrystalline aggregates Nonexistent Almost opaque M1, M2 RH Fe-oxyhydroxides, celadonite Very high FeO_t, low SiO₂ Iddingsite

Notes: M1= vesicle or cavity linings or fillings; M2 = fracture and veins coatings and fillings; M3 = pseudomorphic replacement; M4 = patches within mesostasis; GI = gray interior; TZ = transition zone between oxidation halos and gray interior; RH = red halos; GH = green halos. Made following the scheme of Laverne et al. (1996).