iridium
C1Technical / Scientific
Definition
Meaning
A very hard, brittle, silvery-white transition metal of the platinum group, with atomic number 77, and symbol Ir.
A dense, corrosion-resistant metal used in specialist scientific and industrial applications. It is also significant in geology due to its anomalously high abundance in certain geological layers, which is a key piece of evidence for an asteroid impact event theorised to have caused the Cretaceous–Paleogene extinction.
Linguistics
Semantic Notes
Almost exclusively a scientific term. It may be used metaphorically in scientific contexts to signify rarity or resilience, but this is not common in everyday language.
Dialectal Variation
British vs American Usage
Differences
No significant differences in usage. Pronunciation and spelling are identical.
Connotations
Identical technical connotations.
Frequency
Identical and very low frequency in non-specialist discourse.
Vocabulary
Collocations
Grammar
Valency Patterns
The [NOUN] is made of/contains/uses iridium.Iridium is used in/for [NOUN PHRASE].Vocabulary
Synonyms
Strong
Neutral
Weak
Vocabulary
Antonyms
Phrases
Idioms & Phrases
- “None. 'Iridium' does not feature in common English idioms.”
Usage
Context Usage
Business
Only in highly specialised industrial or mining reports.
Academic
Chemistry, physics, geology, materials science, and engineering contexts.
Everyday
Virtually never used. A layperson might encounter it in popular science articles about dinosaurs or space.
Technical
The primary domain: scientific literature, patents, and technical specifications for high-performance equipment.
Examples
By Part of Speech
verb
British English
- Not applicable; no verb form.
American English
- Not applicable; no verb form.
adverb
British English
- Not applicable; no adverb form.
American English
- Not applicable; no adverb form.
adjective
British English
- The meteorite's iridium content was analysed.
- An iridium-tipped pen nib.
American English
- The impact layer is rich in iridium material.
- Iridium-coated electrodes were used.
Examples
By CEFR Level
- Iridium is a very hard metal.
- Spark plugs can be made with a tiny piece of iridium.
- The high level of iridium found in the clay layer supports the theory of a massive asteroid impact.
- Osmium–iridium alloys are employed where extreme hardness and durability are required, such as in the bearings of precision compasses.
Learning
Memory Aids
Mnemonic
Imagine a very rare, IRIdescent metal that's as hard as a dIUmOnD. Iridium sounds like a mix of 'iridescent' and 'diamond'.
Conceptual Metaphor
METAL AS A SIGNATURE/TELLTALE SIGN (in geology: the iridium layer as a 'fingerprint' of an asteroid impact).
Watch out
Common Pitfalls
Translation Traps (for Russian speakers)
- Direct translation is 'иридий' (iridiy). No false friends; it is a precise scientific cognate.
Common Mistakes
- Misspelling: 'iridum', 'irridium'. Mispronunciation: /aɪˈrɪdiəm/ (eye-rid-ium) is less common than the standard /ɪˈrɪdiəm/ (ih-rid-ium).
Practice
Quiz
What is the primary significance of the 'iridium anomaly' in geology?
FAQ
Frequently Asked Questions
Yes, it is a precious metal, typically more expensive than gold due to its rarity and difficulty in extraction and processing.
In high-performance spark plugs for vehicles, specialized scientific equipment, and as a hardening agent in platinum alloys for jewellery and industrial applications.
A thin global layer of sediment, rich in iridium (which is rare on Earth's surface but common in asteroids), coincides with the extinction of the dinosaurs. This 'iridium layer' is a key piece of evidence for the Alvarez hypothesis that an asteroid impact caused the mass extinction.
Naturally occurring iridium has two stable isotopes and is not radioactive. However, the isotope iridium-192 is artificially produced and is radioactive, used in industrial radiography and cancer treatment.