Epidote
A calcium aluminium iron sorosilicate widely occurring during low- to medium-grade metamorphism and alteration.
Language and route: French épidote coined by Haüy from Ancient Greek ἐπίδοσις (epídosis), usually glossed increase; literal semantic nuance disputed. French épidote coined by Haüy from Ancient Greek ἐπίδοσις (epídosis), usually glossed increase; literal semantic nuance disputed
Literal gloss: increase or addition (qualified)
The name and its history
René-Just Haüy · c.1801; original named page not transcribed
- What does the word literally mean?
- Immediate borrowing or word-formation route: French épidote coined by Haüy from Ancient Greek ἐπίδοσις (epídosis), usually glossed increase; literal semantic nuance disputed. Source form: ἐπίδοσις (epídosis), glossed ‘addition / increase (contextually disputed gloss)’. Conventional short gloss: ‘increase or addition (qualified)’. A literal gloss and the historical reason for naming must be distinguished.
- What did the original author mean?
- Haüy introduced épidote around 1801, associated with the unequal extension of one side of a crystal base.
- Why was the name needed?
- A descriptive crystal habit needed separation from other minerals grouped by superficial resemblance.
- What evidence supported the original concept?
- Crystallographic form and measurement mattered to Haüy; precise translation of Greek epídosis versus his intended analogy is debated.
- How has geology changed the concept?
- Epidote group chemistry and mineral reactions are now central to alteration and metamorphic interpretation; colour/shape no longer suffice.
Further historical context
Haüy introduced épidote around 1801, associated with the unequal extension of one side of a crystal base.
A descriptive crystal habit needed separation from other minerals grouped by superficial resemblance.
Crystallographic form and measurement mattered to Haüy; precise translation of Greek epídosis versus his intended analogy is debated.
Epidote group chemistry and mineral reactions are now central to alteration and metamorphic interpretation; colour/shape no longer suffice.
Editorial qualification
Haüy naming sense supported by secondary crystallographic discussion; Greek semantic gloss is disputed and the original passage is not independently transcribed.
Related names
Sources
- Mindat — Epidote nomenclature discussion — discussion of Greek epidosis and Haüy 1801 crystallographic motive, disputed literal gloss
- British Geological Survey — rock classification — present petrographic framework, not evidence of historical first use
- IUGS recommendations on high-pressure rocks — modern assemblage versus facies naming safeguards