What does feldspath mean?
Feldspath is a variant spelling of feldspar, the name given to a large group of rock-forming minerals that together constitute an enormous share of the Earth's crust. Feldspars are aluminosilicates of potassium, sodium, or calcium, appearing in colours ranging from white and grey to pink and green, and they are essential components of granite, gneiss, and many other igneous and metamorphic rocks. Beyond geology, the mineral has long been industrially important: ground feldspar serves as a flux in ceramics and glassmaking and as a filler in paints and plastics. The spelling 'feldspath' reflects the word's German origins and persists mainly in older literature or in continental European usage, while modern English science writing standardises on 'feldspar'. For general readers, encountering 'feldspath' almost always signals either a historical text or a translation rather than a different mineral altogether.
nounFeldspath is a rare variant spelling of feldspar, referring to any of a group of abundant rock-forming aluminosilicate minerals containing sodium, potassium, or calcium, which make up a large proportion of the Earth's crust.
- A variant form of feldspar: any of a group of hard aluminosilicate minerals (such as orthoclase and plagioclase) that are major constituents of igneous and metamorphic rocks.
"The granite's pink hue came from grains of feldspath scattered throughout the rock."
"Veins of white feldspath ran through the otherwise grey quarry face."
"Potters prized the feldspath for the way it lowered the firing temperature of their glazes."
As a mineral-group name it usually functions as a mass noun; the plural appears only when counting distinct varieties or specimens.
"The collection included feldspaths from several Norwegian localities."
This one mineral family makes up roughly half of the Earth's crust — and 'feldspath' is its lesser-seen alternate spelling, borrowed straight from the German.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Etymology of feldspath
The word derives from the German 'Feldspath' (modern German 'Feldspat'), a compound of 'Feld' meaning field and 'Spat' meaning a splintery stone or spar — so literally, 'field spar', a name reportedly coined because early observers found crystals weathered out of tilled fields. It entered English in the mid-18th century as mineralogy adopted German terminology. The related form 'feldspar' became the dominant English spelling, while 'feldspath' survives chiefly as a historical or continental variant.
Related word forms
How feldspath is actually used
In contemporary English scientific writing, 'feldspar' is overwhelmingly the preferred form; 'feldspath' appears mainly in older texts, in translations, or under French and German influence. It is a mass noun like most mineral names and is not normally pluralized except when referring to distinct varieties.
Easily confused with feldspath
Feldspar is the standard modern spelling of the mineral name, while feldspath is an older or chiefly continental European variant of the same word.