Feldspar
A major family of framework silicate minerals, notably alkali feldspars and plagioclase, abundant in igneous and metamorphic rocks.
Language and route: German Feldspat → English feldspar. English derives from German Feldspat, literally the elements Feld ‘field’ and Spat ‘spar, readily cleavable mineral’; the reason for the first element is historically disputed.
Literal gloss: field spar
The name and its history
German mineralogical vernacular; no single first coiner established · Attested German and English forms in the eighteenth century
- What does the word literally mean?
- ‘Field spar’ as components; exact motivation for ‘field’ uncertain.
- What did the original author mean?
- In eighteenth-century mineral classification the term grouped pale, cleavable silicate minerals that were not yet chemically or crystallographically separated as modern feldspar species.
- Why was the name needed?
- A practical mining/mineralogical name was needed for minerals occurring across many different crystalline rocks, before analyses clarified alkali feldspar versus plagioclase.
- What evidence supported the original concept?
- Shared cleavage and hand-specimen appearance were the principal early evidence. A 1911 historical dictionary notes Richard Kirwan’s 1794 form felspar and its different interpretation of the first element.
- How has geology changed the concept?
- Modern feldspar is a group subdivided by composition and crystal structure. The historical spelling and ‘field’ etymology do not specify the geology of its occurrence.
Further historical context
The English variation feldspar/felspar is itself a small history of reinterpretation: written English has sometimes omitted the d under the impression that the element referred to rock rather than fields.
Editorial qualification
The compound elements are clear; the precise rationale for Feld has competing historical accounts.
Related names
Granite · Aplite · Pegmatite · Quartz · Igneous · Metamorphic · Plagioclase · Orthoclase · Microcline · Sanidine · Albite · Anorthite · Oligoclase · Labradorite · Andesine · Bytownite · QAPF classification · Alkali feldspar · Syenite · Monzonite · Granodiorite
Sources
- Online Etymology Dictionary, feldspar — German-to-English linguistic transmission
- Encyclopaedia Britannica (1911), Felspar — Historical evidence of competing English spelling and 1794 rationale