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earth science

Icelandite

Icelandite is a earth science topic covered in the lgStudy science library. This page brings together a partial reference excerpt, illustrations, worked examples, real-world applications and a short study plan, so you can understand Icelandite rather than just read about it. In short: Icelandite is a type of volcanic rock, an andesite that is enriched in iron but deficient in aluminium (< 16.5% Al2O3). Icelandites are between rhyodacite and tholeiitic basalt in composition and contain andesine, hypersthene and augite, with a silica (SiO2) content greater than 60%.

Icelandite — main illustration
Icelandite — illustration

Key takeaways

  • Icelandite belongs to earth science; place it in that map before memorising details.
  • Learn the definition first, then one example that makes the definition concrete.
  • Connect Icelandite to a quantity you can measure, compute or draw — that is where exam questions come from.
  • Reproduce the core statement of Icelandite from memory before moving on to harder problems.

Reference excerpt

Icelandite is a type of volcanic rock, an andesite that is enriched in iron but deficient in aluminium (< 16.5% Al2O3). Icelandites are between rhyodacite and tholeiitic basalt in composition and contain andesine, hypersthene and augite, with a silica (SiO2) content greater than 60%.

The name was coined by the British geologist Ian S. E. Carmichael (who later became professor at the University of California, Berkeley) while working around 1960 on his PhD thesis at a Cenozoic volcano near the parsonage Thingmuli (Þingmúli) in East Iceland. For continental cogenetic series of volcanic rocks it is generally the case that the concentration of iron decreases with increasing silica content, but at Þingmúli the opposite was true, leading Carmichael to the conclusion that the iron-rich intermediate rock deserved its own name, icelandite. With its elevated iron content and low aluminium content compared with calc-alkaline andesite, icelandite is assigned instead to the tholeiitic magma series.

References

Illustrations

Icelandite: Icelandite is field O2 in the TAS classification.
Icelandite is field O2 in the TAS classification.

Worked examples

Example 1 — a first encounter with Icelandite

Start with the simplest possible case. Write down what Icelandite claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In earth science, the smallest case is usually a single object, a single equation or a single measurement. Check that every symbol or term in your sentence has a meaning in that case.

Example 2 — changing one variable

Take the situation from Example 1 and change exactly one quantity: double it, halve it, or set it to zero. Predict what should happen to Icelandite before you calculate. Comparing your prediction with the result is the fastest way to find out whether you understand the idea or only the words.

Example 3 — an exam-style question

Typical questions about Icelandite ask you to (a) state it precisely, (b) apply it to given data, and (c) explain a limitation. Practise writing all three answers in under five minutes; the third part is what separates a full-mark answer from an average one.

Applications of Icelandite

In research
Icelandite appears in earth science research whenever the underlying quantities have to be modelled precisely. Papers usually cite it as a starting assumption and then explore where it breaks down.
In technology and industry
Engineering practice reuses Icelandite in design rules, simulations and safety margins. Knowing the idea lets you read a specification sheet and understand why the numbers look the way they do.
In the classroom
Icelandite is common in secondary-school and first-year university syllabi. It links to neighbouring topics Andesite, Volcanology stubs, so understanding it makes those chapters shorter.
In everyday life
Look for Icelandite outside the textbook — in sport, cooking, traffic, electronics or the sky above you. An example you found yourself is remembered far longer than one you were given.

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How to study Icelandite in 20 minutes

  1. Read the reference excerpt below once, without taking notes.
  2. Close the page and write down what Icelandite means in your own words.
  3. Compare your version with the excerpt and mark what you missed.
  4. Work through the three examples above with pen and paper.
  5. Explain Icelandite out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Icelandite in simple terms?

Icelandite is a type of volcanic rock, an andesite that is enriched in iron but deficient in aluminium (< 16.5% Al2O3). Icelandites are between rhyodacite and tholeiitic basalt in composition and contain andesine, hypersthene and augite, with a silica (SiO2) content greater than 60%.

Why does Icelandite matter?

Because it connects several earth science ideas at once: it gives you a definition you can apply, a quantity you can calculate, and a way to check whether a result is plausible.

How should I study Icelandite?

Read the excerpt, restate it from memory, then work through the examples and applications listed on this page. The five-step study plan above takes about twenty minutes.

What does this page cover?

It gives you a compact reference excerpt plus original lgStudy explanations, examples, applications and study material on Icelandite.

Tags

  • Andesite
  • Volcanology stubs

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