What does felspathoid mean?
Felspathoid is a specialist geological adjective meaning resembling feldspar or belonging to a group of feldspar-related minerals. Feldspars are among the most abundant minerals in Earth’s crust and occur widely in igneous rocks such as granite, as well as in many metamorphic and sedimentary formations. In technical mineralogy, the related noun “felspathoid” can denote a mineral treated as resembling or closely related to feldspar. The term is most useful when a specimen or mineral structure has feldspar-like characteristics but does not require identification as a specific feldspar species. Because it is chiefly a technical term, “felspathoid” is uncommon in everyday English and tends to appear in descriptions of mineralogy, petrography, and the microscopic study of rocks.
Resembling feldspar in appearance or structure, or belonging to the felspathoid group of minerals.
"The rock contains felspathoid crystals with a glassy luster."
Chiefly used in geological and mineralogical writing.
A mineral or mineral group regarded as resembling or closely related to feldspar.
"The analyser identified the pale mineral as a felspathoid."
A specialist mineralogical noun, less common than the adjective.
The plural is used when referring to multiple minerals or mineral groups of this kind.
"Several felspathoids occur in the metamorphic rock."
Some of the most familiar rocks are built in part from feldspar-like minerals known as felspathoids.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does felspathoid come from?
The word combines an English form of feldspar with the suffix -oid, meaning “resembling” or “like.” Its development reflects the broader formation of English mineral names from Greek-derived descriptive suffixes. The base word feldspar itself has Germanic roots, through German Feldspat, traditionally interpreted as “field spar.”
How felspathoid is actually used
This is a specialist geological and mineralogical term. It is uncommon in general prose and is normally used in technical descriptions of minerals, rocks, and crystal structures.
Easily confused with felspathoid
Feldspar is a specific group of rock-forming aluminosilicate minerals, whereas felspathoid describes a mineral or structure resembling feldspar.