Table 2. Mineral stoichiometries and abundances (weight percent) in the Daniel Springs weathering profile.

Table 2. Mineral stoichiometries and abundances (weight fraction) in the Daniel Springs weathering profile. Abundances given below are normalized to unity and constrained by XRD, thin section petrography and coloration.

Mineral	Formula	A-horizon 0-17 cm	B-horizon 17-90 cm	C-horizon90-300 cm	Parent rock > 300 cm
Plagioclase	Na_0.58Ca_0.42Al_1.42Si_2.58O₈	0.000	0.068	0.258	0.440
Hornblende	Na_0.45Ca_1.90Mg_2.33 Fe²⁺_1.98 Al_0.80Si_6.53Al_1.45Ti_0.02O₂₂ (OH)₂	0.000	0.115	0.307	0.400
Epidote	Ca_1.96 Fe³⁺_0.77 Al_2.23Si_3.00O₁₂ (OH)	0.000	0.013	0.024	0.030
^Biotite	K_0.86Mg_1.21 Ti_0.09 Fe²⁺_1.25 Al_0.40Si_3.00Al_1.00O₁₀ (OH)₂	0.000	0.000	0.013	0.040
Quartz	SiO₂	0.317	0.207	0.095	0.060
Ilmenite	(FeO)_0.40(Fe₂O₃)_0.40 (TiO₂)_0.20	0.000	0.003	0.004	0.030
Vermiculite	K_0.35Mg_1.21 Ti_0.09 Fe³⁺_0.31 Fe²⁺_0.63 Al_0.40Si_3.00Al_1.00O₁₀ (OH)₂	0.000	0.010	0.083	0.000
Kaolin	Al₂Si₂O₅(OH)₄	0.579	0.567	0.207	0.000
*Goethite - low-Al	Al_0.1Fe_0.9O(OH)	0.010	0.007	0.001	0.000
*Goethite - high-Al	Al_0.3Fe_0.7O(OH)	0.005	0.003	0.000	0.000
Hematite	Fe₂O₃	0.012	0.009	0.009	0.000
^#HIV	Ca_0.08K_0.24Mg_0.20 Fe³⁺_0.24 Al_2.21Si_3.23O_15.79 H_5.79	0.078	0.000	0.000	0.000
^…Anatase	Fe_0.05 Ti_0.95 O₂ (OH)_0.05	0.004	0.001	0.000	0.000

^{Composition modified from Schroeder et al, (1997). * Composition from Melear and Schroeder (1998). ^# Composition from Kirkland and Hajek, (1972), ^…Composition from Shiflet (1999).}