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LITHOEN

Mineral

Muscovite

The common white mica: a sheet silicate whose perfect basal cleavage follows the planes of its structure, and whose platy grains align under directed pressure to make foliation.

Silvery platy muscovite crystals intergrown with white blocky albite.
Muscovite intergrown with albite. Muscovite is a sheet silicate whose perfect basal cleavage follows the planes of its structure; albite is the sodium end member of the plagioclase series.

Robert M. Lavinsky, CC BY-SA 3.0 · CC-BY-SA-3.0 · source

Classification

formula
KAl2(Si3Al)O10(OH)2
ima status
approved
crystal system
monoclinic

How this record is known

4
Settled consensus
Cited as the accepted position of the discipline.

4 of 4 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.

Established2.5 on the Mohs scale

Muscovite is monoclinic with a hardness of about 2.5 — soft, and softest across the planes on which its sheet structure cleaves.

  • precision note: The Handbook records hardness as directionally variable for muscovite; the value here is the lower, cross-cleavage figure it gives.

Evidence support: Supported by the cited evidence one source

Evidence: Mineral Data Publishing 2001 Institutional reference

EstablishedMonoclinic

The Handbook of Mineralogy records the crystal data of muscovite as monoclinic.

Evidence support: Supported by the cited evidence one source

Evidence: Mineral Data Publishing 2001 Institutional reference

Established2.77–2.88 g/cm3

The Handbook of Mineralogy gives a measured density for muscovite of 2.77–2.88 g/cm3.

  • method: Compiled from published measurements; Lithoen holds no measurement of its own.
  • precision note: The data sheet gives a range of measured densities, not a single value. An earlier version of this claim published 2.82 g/cm3 — approximately the midpoint — and attributed it to the Handbook, which states no representative value. Lithoen now publishes the range the source gives. Where the Handbook does state a single measured density, as for quartz, the corpus carries that value as a scalar.

Evidence support: Supported by the cited evidence one source

Evidence: Mineral Data Publishing 2001 Institutional reference

EstablishedKAl2(Si3Al)O10(OH)2

Muscovite is an accepted mineral species in the IMA List of Minerals, with the CNMNC-approved formula KAl2(Si3Al)O10(OH)2 and IMA status “approved”.

  • definition basis: IMA List of Minerals, September 2026 update, which is the authority on mineral species status.
  • precision note: An approved formula is an idealised composition; natural crystals of most species depart from it through substitution.

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

Figures

Five groups of triangles representing silicon-oxygen tetrahedra, arranged as isolated units, a single chain, a double chain, a sheet and a framework, each labelled with example minerals and a silicon-to-oxygen ratio.
SchematicHow silicon–oxygen tetrahedra link, and what each arrangement produces. Sharing more oxygens between tetrahedra lowers the oxygen content relative to silicon, from 1:4 in isolated tetrahedra to 1:2 in a framework — which is why the structural class can be read from the formula.
Full description of this figure

The diagram sets out five structural classes of silicate. Isolated tetrahedra share no oxygens and give Si:O of 1:4, as in olivine and garnet. Single chains share two oxygens per tetrahedron, giving 1:3, as in pyroxene. Double chains share two and three alternately, giving 4:11, as in amphibole. Sheets share three, giving 2:5, as in mica and clay. Frameworks share all four, giving 1:2, as in quartz and feldspar. Moving left to right is a progression of increasing polymerisation.

Original Lithoen diagram · LITHOEN-ORIGINAL

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