Predominance

What Predominance does

Track boundaries, not the whole field

A predominance study follows the lines where one expression gives way to another instead of evaluating everything either side of them, so a sharp diagram costs a fraction of the simulations a lattice of the same sharpness would need.

Any two axes

Classically pe against pH — an Eh–pH or Pourbaix diagram — but the axes can be anything the model depends on: temperature, a total concentration, a partial pressure.

Second and third rank

Each expression is reported at a level: predominant, sub-predominant, sub-sub-predominant. A species that never dominates anywhere can still be the interesting one.

Masks, labels and your samples

Constraint areas restrict the diagram to where it means something — the water stability limits are the usual case — labels name the fields, and scatter traces put your field samples on top.

Typical uses

• Eh–pH diagrams for redox-sensitive elements
• Mineral stability fields over pH and activity
• Comparing predominance between thermodynamic databases