earth science

Hawaiite

Hawaiite 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 Hawaiite rather than just read about it. In short: Hawaiite is an olivine basalt with a composition between alkali basalt and mugearite. It was first used as a name for some lavas found on the island of Hawaii.

Key takeaways

Hawaiite 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 Hawaiite to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Hawaiite from memory before moving on to harder problems.

Reference excerpt

Hawaiite is an olivine basalt with a composition between alkali basalt and mugearite. It was first used as a name for some lavas found on the island of Hawaii. It occurs during the later stages of volcanic activity on oceanic islands such as Hawaii, which happens to be when the alkali metals are most present. In gemology, hawaiite is a colloquial term for Hawaii-originated peridot, which is a gem-quality form of the mineral olivine.

Description

Hawaiite is an aphanitic (fine-grained) volcanic rock produced by rapid cooling of lava moderately poor in silica and enriched in alkali metal oxides (potassium oxide plus sodium oxide). It is often impractical to determine the mineral composition of such a fine-grained rock, and so hawaiite is defined chemically. Under the TAS classification, hawaiite is sodic trachybasalt, with a silica content close to 49 wt%, a total alkali metal oxide content close to 6%, and Na2O wt% > K2O wt% + 2. This places hawaiite in the S1 field of the TAS diagram. Hawaiite is not a recognized rock type in the QAPF classification of igneous rock, which is based on the relative proportions of quartz, alkali feldspar, and plagioclase in the mineral composition. However, hawaiite is composed mostly of andesine (plagioclase feldspar with an albite content of 50% to 70%) and pyroxene with smaller amounts of olivine. This would fall into the andesite/basalt field of the QAPF diagram.

Occurrence Hawaiite is erupted in the late stages of ocean island volcanism, forming part of the alkaline magma series characteristic of such eruptions. It is preceded by silica-poor ankaramite and followed by intermediate-silica mugearite as the magma evolves by crystallization in the underlying magma chamber. These rocks form an alkalic cap over the older rocks of the island. Hawaiite can occur at earlier stages in the evolution of some volcanoes in other tectonic settings, for example during the middle stage of volcanic activity in the Kekuknai volcanic massif (in Kamchatka, Russia) that formed in a volcanic back-arc basin. Other settings in which hawaiite and other alkaline volcanic rocks are found include regions of continental extension, such as the Basin and Range Province of western North America and the Red Sea Rift.

References

Worked examples

Example 1 — a first encounter with Hawaiite

Start with the simplest possible case. Write down what Hawaiite 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 Hawaiite 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 Hawaiite 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 Hawaiite

In research: Hawaiite 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 Hawaiite 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: Hawaiite is common in secondary-school and first-year university syllabi. It links to neighbouring topics Aphanitic rocks, Basalt, Mafic rocks, so understanding it makes those chapters shorter.
In everyday life: Look for Hawaiite 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 Hawaiite in 20 minutes

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

Frequently asked questions

What is Hawaiite in simple terms?

Hawaiite is an olivine basalt with a composition between alkali basalt and mugearite. It was first used as a name for some lavas found on the island of Hawaii.

Why does Hawaiite 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 Hawaiite?

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 Hawaiite.