EASC 2502 Module 4: Geochemical Classification of the Elements

What is a major element?

A major constituent of rocks and minerals, >1 wt%

What is a minor element?

A minor constituent of rocks and minerals, 1-0.1 wt%

What are trace elements?

Trace constituent of rocks and minerals, in ppm or ppb

What are refractory elements?

Early condensates that condense at T>1400K

What are transitional refractory elements?

Silicates and metals, condense at 1000-1400K

What are moderately volatile elements?

Condense at 800-1000K

What are highly volatile elements?

Condense at T<800K

What is Goldschmidt classification?

Classifying elements based on behavior in Earth's reservoirs

What are the 4 Goldschmidt classes?

Lithophile

Chalcophile

Siderophile

Atmophile

How are elements classified by partition behavior and charge/radius?

Compatible vs incompatible

What are low field strength elements (LFSE)? Also called LILE. How compatible are they?

Cations with large radii to charge (ir/ic > 0.2). Generally highly incompatible.

Cs, Rb, K, Ba, Sr, Th, U, and Pb

What are high field strength elements (HFSE)? How compatible are they?

Cations with small radii to charge (ir/ic < 0.2). Generally highly incompatible.

Zr, Hf, Nb, Ta, Y, ±Sc, Ti, P

What are rare earth elements (REE)? How compatible are they?

Largely trivalent cations of the lanthanide series. Generally incompatible.

La, Ce, Pr, Nd, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Lu.

How are REE further subdivided?

Divided into light, medium, and heavy REE.

What are transition elements (TE)? How compatible are they?

Metals in the middle of the periodic table. They have multiple redox states. Moderately compatible.

Cr, Ni, Sc, V, Co, Cu, Zn ± Ti, Fe, Mn

What are noble metals? How compatible are they?

Platinum group elements and other metals. Highly compatible.

Pt, Pd, Ir, Os, Ru, Rh, Au, Ag, Re

What are base metals? How compatible are they?

Metals that commonly form most ore deposits. Highly compatible.

Cu, Zn, Pb

What are volatile elements?

Pathfinder elements in ore systems often transported by volatiles during magmatism or hydrothermal fluids.

Cd, In, Sn, Sb, As, Hg, Tl, Bi