Biotite
A commonly used group or compositional-range name for dark trioctahedral micas, rather than one IMA-approved discrete species.
Language and route: German eponym ← French surname. The name honours Jean-Baptiste Biot and is not a Greek description of a physical property.
Literal gloss: named for Jean-Baptiste Biot
The name and its history
Johann Friedrich Ludwig Hausmann · 1847
- What does the word literally mean?
- The transmitted name is The name honours Jean-Baptiste Biot and is not a Greek description of a physical property. The short gloss ‘named for Jean-Baptiste Biot’ is a guide to the naming allusion, not by itself a modern mineralogical definition.
- What did the original author mean?
- Hausmann named biotite in 1847 to commemorate Biot’s work on mica optics, while field geologists continued to recognise familiar dark mica flakes.
- Why was the name needed?
- The naming distinguished and celebrated an optically studied mica group when properties of coloured mineral sheets were of high classificatory interest.
- What evidence supported the original concept?
- Mica optical behaviour, thin-sheet cleavage and nineteenth-century mineral descriptions supplied the science behind the commemoration.
- How has geology changed the concept?
- The IMA 1998 revision treats biotite as a series/group-level name, not a single accepted species. Unanalysed ‘biotite’ may represent several species.
Further historical context
Hausmann named biotite in 1847 to commemorate Biot’s work on mica optics, while field geologists continued to recognise familiar dark mica flakes.
The naming distinguished and celebrated an optically studied mica group when properties of coloured mineral sheets were of high classificatory interest.
Mica optical behaviour, thin-sheet cleavage and nineteenth-century mineral descriptions supplied the science behind the commemoration.
The IMA 1998 revision treats biotite as a series/group-level name, not a single accepted species. Unanalysed ‘biotite’ may represent several species.
Related names
Mica · Muscovite · Phlogopite · Hornblende
Sources
- Mindat, Biotite — Hausmann (1847) — Eponym for Biot; current group/series, not discrete species
- Rieder et al. (1998), Nomenclature of the micas — 1998 revision: biotite is no longer a species name
- Mindat, Mica Group — Historic appearance-based name and modern sheet-silicate group
- IMA–CNMNC, List of Mineral Names (updated September 2026) — Contemporary mineral-species standing; consult live master list