Progressive removal of crystals from a cooling magma, so that the remaining liquid drifts away from the composition it started with. Elements excluded from the crystals accumulate in what is left.
SchematicWhether an element enters a growing crystal or stays in the melt depends on how well its charge and radius fit the lattice site on offer. The partition coefficient D expresses that as a ratio — but it is a ratio for one cation, one site and one set of conditions, not a property of the element.Full description of this figure
On the left, a crystal is drawn with three lattice sites of fixed size, each holding a cation. A cation whose charge and radius fit a site is taken into the crystal and is called compatible, with a partition coefficient greater than one. On the right, a melt is drawn as a disordered field able to accommodate cations of any size; a cation that fits the crystal sites poorly is left there and is called incompatible, with a partition coefficient below one. Arrows run in both directions between the two. The partition coefficient D is defined as the concentration in the crystal divided by the concentration in the melt. The figure is labelled schematic and carries the caution that compatibility is a property of a cation in a particular site under particular conditions.
Original Lithoen diagram · LITHOEN-ORIGINAL
How this record is known
1
Interpretation
Reached by reasoning from evidence, or produced by a named model.
1 of 1 claims on this page cite at least one registered source. Counts describe how each statement is known, not how likely it is to be true.
What Lithoen records
Each claim states how it is known and cites its evidence.
InferredProgressive crystal removal shifts the residual liquid’s composition.
Removing crystals from a cooling magma drives the remaining liquid away from its starting composition: elements that entered the crystals are depleted in the residual melt, and those excluded from them accumulate.
method: Follows from partitioning applied repeatedly as crystallisation proceeds.
precision note: The corpus asserts the mechanism, not any particular idealised crystallisation sequence; no source retrieved in Phase 2 supports presenting one as a universal path.
Evidence support: Supported by the cited evidence· 2 sources, multiple sources, independence unknown
