 Elemental classification  Lewis acid/base  Pearson’s hard/soft metals  Ionic and covalent index  Ionic potentials  Earth Scientist's Periodic Table of the Elements and Their Ions  Common minerals and aqueous species in soils  Familiar with equilibrium reactions  Use log activity-pH graphs Trace metals review

Elemental Distribution in Sedimentary Rocks based on IP Accumulation of minor elements in SR is linked to IP (z/r) and metal solubility in water IP<2.5 (low IP) 2.5  IP<9.5 (Intermediate) IP>9.5 (High IP) Ba, Li, Rb, Sr ( remain in solution ) REEs, Cu, Ni, Pb, U, Zn, Zr, Tl, Sc, Ge, Cr, Co,….( will precipitate ) As, B, Mo, Se ( will form oxyanions ) If H—O > M—O: M remains in solution (poor incorporation in rocks) If H—O < M—O: M appropriates one or more O from water molecules forming oxyanions and releasing H + : Se H 2 O  SeO H + If H—O  Me—O: leads to the formation of an insoluble hydroxide: Zn H 2 O  Zn(OH) 2 + 2H + JCB lecture 1/13

Classification based on IP  Medium IP  Medium IP ( )  Strong bond w/ O-enter early in igneous rocks  Make oxides-insoluble  Concentrated in soils  Not nutrients  Least depleted from the mantle  Low IP  Low IP (<2.5)  Weak bond w/ O-enter late in igneous rocks  Make fluoride minerals-soluble  Abundant in rivers and seawaters  Serves as nutrients

Ag Hg FHard Cl Br ISoft Mg Na

 Hard metals: are more likely to form oxides, carbonates, nitrides and fluorides ( O, N, and F )  Soft metals: are more likely to form phosphides, sulfides and selinides ( P, S, Cl, Br and I ).

Classification based on IP  Medium IP  Medium IP ( )  Strong bond w/ O-enter early in igneous rocks  Make oxides-insoluble  Concentrated in soils  Not nutrients  Least depleted from the mantle  Low IP  Low IP (<2.5)  Weak bond w/ O-enter late in igneous rocks  Make fluoride minerals-soluble  Abundant in rivers and seawaters  Serves as nutrients  High IP  High IP (>9.5)  Strongest bond w/ O-enter really late in igneous rocks  Make oxyanions-soluble  Abundant in rivers and seawaters  Serves as nutrients

Fig. 1 Elemental speciation in aqueous solution Low T/Late crystalization Soluble  nutrients High T/early crystalization Insoluble  not nutrients Too late crystalization Soluble  nutrients

2.3. Goldschmidt’s Geochemical Classification SIDEROPHILE: They occur with native iron: Fe, Co, Ni, Ru, Rh, Pd, Re, Os, Ir, Pt, Au, Mo, Ge, Sn, C, P, (Pb), (As), (W) CHALCOPHILE: Concentrated in sulfides: Cu, Ag, (Au), Zn, Cd, Hg, Ga, In, Tl, (Ge), (Sn), Pb, As, Sb, Bi, S, Se, Te, (Fe), (Mo), (Re) LITHOPHILE: Associated with silicates Li, Na, K, Rb, Cs, Be, Mg, Ca, Sr, Ba, (Pb), B, Al, Sc, Y, REE, (C), Si, Ti, Zr, Hf, Th, (P), V, Nb, Ta, O, Cr, W, U, (Fe), Mn, F, Cl, I, (H), (Tl), (Ga), (Ge), (N) ATMOPHILE: prevalent in gas phase H, N, (C), (O), (F), (Cl), (Br), (I), He, Ne, Ar, Kr, Xe Center of the Periodic Table (mostly noble metals) Right of the Periodic Table Left of center of the Periodic Table Extreme right of the Periodic Table JCB lecture 1/13

JCB lecture Hard cations Intermediatecations Intermediate cations

Classification based on hard/soft cations  Hard cations  Lithophile-Si  Intermediatecations  Intermediate cations  Siderphile-Fe  Soft cations  Chalcophile-S

Chemical Equilibria in Soils (Lindsay, 1979)