plagioclase: meaning, definition, pronunciation and examples
Very low (specialist vocabulary)Technical/Scientific
Quick answer
What does “plagioclase” mean?
A common rock-forming mineral of the feldspar group, consisting of a continuous series from albite (sodium aluminium silicate) to anorthite (calcium aluminium silicate).
Audio
Pronunciation
Definition
Meaning and Definition
A common rock-forming mineral of the feldspar group, consisting of a continuous series from albite (sodium aluminium silicate) to anorthite (calcium aluminium silicate).
In geology and mineralogy, it refers to a group of triclinic feldspars that are major constituents of many igneous and metamorphic rocks, often identified by their characteristic striations.
Dialectal Variation
British vs American Usage
Differences
No differences in meaning, spelling, or usage. Pronunciation may have minor stress/intonation variation.
Connotations
Identical technical connotations in both varieties.
Frequency
Equally rare outside specialist contexts in both regions.
Grammar
How to Use “plagioclase” in a Sentence
[Adjective] + plagioclase (e.g., twinned plagioclase)plagioclase + [of + NP] (e.g., plagioclase of intermediate composition)plagioclase + [in + NP] (e.g., plagioclase in the gabbro)Vocabulary
Collocations
Examples
Examples of “plagioclase” in a Sentence
adjective
British English
- The plagioclase component was analysed.
- A plagioclase-rich layer.
American English
- The rock has a high plagioclase content.
- Plagioclase minerals were separated.
Usage
Meaning in Context
Business
Never used.
Academic
Exclusively used in geological sciences, common in research papers, textbooks, and lectures on petrology.
Everyday
Virtually never used. Would be unfamiliar to the general public.
Technical
Core, essential term in mineralogy, igneous petrology, and geochemistry.
Vocabulary
Synonyms of “plagioclase”
Neutral
Weak
Watch out
Common Mistakes When Using “plagioclase”
- Mispronouncing the 'g' as a hard /g/ (like in 'go') instead of a soft /dʒ/ (like in 'judge').
- Confusing it with 'orthoclase', another type of feldspar.
- Misspelling as 'plagiochlase' or 'plagioctase'.
FAQ
Frequently Asked Questions
No, it is a continuous solid solution series between albite (sodium-rich) and anorthite (calcium-rich) end-members.
It often has a white to grey colour, glassy lustre, two good cleavage planes at nearly 90 degrees, and may show fine parallel striations on some surfaces.
Both are feldspars. Plagioclase contains sodium or calcium and is triclinic, often striated. Orthoclase (or alkali feldspar) is potassium-rich and typically monoclinic, without the striations.
It is a major rock-forming mineral. Its composition and texture provide key information about the origin, cooling history, and chemical environment of igneous and metamorphic rocks.
A common rock-forming mineral of the feldspar group, consisting of a continuous series from albite (sodium aluminium silicate) to anorthite (calcium aluminium silicate).
Plagioclase is usually technical/scientific in register.
Plagioclase: in British English it is pronounced /ˈpleɪdʒɪə(ʊ)kleɪz/, and in American English it is pronounced /ˈpleɪdʒiəˌkleɪs/. Tap the audio buttons above to hear it.
Learning
Memory Aids
Mnemonic
Think: 'PLAGIARISM' + 'CLASS'. Imagine a mineral 'stealing' properties (like sodium and calcium) to form a 'class' (series) of related minerals.
Conceptual Metaphor
Not applicable; term is purely referential with no common metaphorical extensions.
Practice
Quiz
In which scientific field is the term 'plagioclase' primarily used?