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LITHOEN

Mineral group

Plagioclase

The continuous solid-solution series between albite and anorthite. A plagioclase composition is a position along that series, which is why the series and not a single formula is the right unit of description.

Classification

group kind
series

How this record is known

2
Settled consensus
Cited as the accepted position of the discipline.

2 of 2 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.

EstablishedCoupled NaSi ⇌ CaAl substitution between albite and anorthite.

The plagioclase series runs from albite, Na(AlSi3O8), to anorthite, Ca(Al2Si2O8). Sodium and silicon are exchanged for calcium and aluminium together, because swapping Na+ for Ca2+ alone would leave the structure with the wrong charge.

  • precision note: Inferred from the two approved formulas, which differ by exactly this coupled exchange; the cited source gives the formulas rather than the substitution mechanism.

Evidence support: Supported by the cited evidence one source

Evidence: Commission on New Minerals, Nomenclature and Classification, International Mineralogical Association 2026 Primary authority

EstablishedNot a species; a series.

“Plagioclase” is not an accepted mineral species: no entry of that name appears in the IMA List of Minerals. It denotes the continuous series between albite and anorthite.

  • definition basis: Absence from the IMA List of Minerals, which is the list of accepted species.
  • precision note: The name remains in ordinary scientific use. It is recorded as a grouping so that it stays usable without being mistaken for a species.

Evidence support: Supported by the cited evidence one source

Evidence: Commission on New Minerals, Nomenclature and Classification, International Mineralogical Association 2026 Primary authority

In the knowledge graph

Record last updated 2026-09-06. Corrections follow the published corrections policy; superseded claims are retained, never silently edited.