Silicates are the component of soil that triggers faster clotting via activation of FXII. (A) FXII activation in plasma by intact, HC, and LC fractionated soils. (B) Clot times of plasma by sterilized (autoclaved) or OM-depleted soils. (C) Endotoxin quantification of soils after treating with a flame for 1 hour (flamed-heated). (D) Clot times of plasma by original and flame-heated soils. (E) Pearson’s correlation between clot times and ζ potential of soils, determined by dynamic light scattering. (F) Pearson’s correlation between clot times and concentration of Si on the surface of soils, determined by TOF-SIMS. Substrate cleavage and clot formation measurements were n = 5 (A, C-F) and n = 3 in triplicate (B). *P < .01; **P < .001. Error bars represent SEM.