earth science

Motukoreaite

Motukoreaite 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 Motukoreaite rather than just read about it. In short: Motukoreaite is a mineral with formula Mg6Al3(OH)18[Na(H2O)6](SO4)2·6H2O (possibly more than one species). The mineral is named for Motukorea, the island in New Zealand where it was discovered.

Key takeaways

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

Reference excerpt

Motukoreaite is a mineral with formula Mg6Al3(OH)18[Na(H2O)6](SO4)2·6H2O (possibly more than one species). The mineral is named for Motukorea, the island in New Zealand where it was discovered. Motukoreaite was first noted in 1941 and officially described in 1977.

Description Motukoreaite occurs as claylike cement or hexagonal tabular crystals up to 0.2 mm (0.0079 in) in size that form rosettes, boxworks, and subparallel aggregates. The crystals are semitransparent and are white, pale yellow, pale yellow-green, or colorless. The mineral readily dehydrates partially. Motukoreaite has been found in association with apatite, barite, calcite, chabazite, calcic plagioclase, gismondine, gypsum, hisingerite, hydrotalcite, limonite, magnetite, montmorillonite, nordstrandite, olivine, phillipsite, pyroxene, quartz, and zeolites.

Formation Motukoreaite forms from the alteration of submarine basaltic glass at temperatures below 150 °C (302 °F). The alteration occurs in the sequence motukoreaite, phillipsite, calcite. A study in 1989 suggested that motukoreaite is a common, widely occurring mineral.

History Motukoreaite was first identified as "beach limestone" by J. A. Bartrum in 1941 at two locations along the shore of Motukorea where it occurs as a coating or alteration of basaltic sand and basaltic tuff related to a small Pleistocene volcanic cone. In 1977, the new mineral was officially described from the island and the name motukoreaite was approved by the Commission on New Minerals and Mineral Names in honor of the island. The mineral's small crystal size made determination of its optical properties difficult.

Distribution Motukoreaite is known from Motukorea, New Zealand, La Piatta quarry in Italy, Stradner Kogel in Austria, and the western Mediterranean Sea near Spain. It has been reported from the Surtsey Island and other locations on the mid-Atlantic Ridge. It also occurs along the axial rift of the Red Sea. The type material is held at the University of Auckland in Auckland, New Zealand, the Natural History Museum, London, and the National Museum of Natural History in Washington, D.C.

References

Bibliography Rodgers, K. A.; Chisholm, J. E.; Davis, R. J.; Nelson, C. S. (September 1977). "Motukoreaite, a new hydrated carbonate, sulphate, and hydroxide of Mg and Al from Auckland, New Zealand" (PDF). Mineralogical Magazine. 41 (319). The Mineralogical Society: 389–390. Bibcode:1977MinM...41..389R. doi:10.1180/S0026461X00038147. S2CID 251023642. Archived from the original (PDF) on 2016-05-27. Retrieved 2012-06-03. Zamarreño, Isabel; Plana, Feliciano; Vazquez, Antonio; Clague, David A. (October 1989). "Motukoreaite: A common alteration product in submarine basalts" (PDF). American Mineralogist. 74 (9–10): 1054–1058.

External links Media related to Motukoreaite at Wikimedia Commons

Illustrations

Worked examples

Example 1 — a first encounter with Motukoreaite

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

In research: Motukoreaite 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 Motukoreaite 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: Motukoreaite is common in secondary-school and first-year university syllabi. It links to neighbouring topics Aluminium minerals, Carbonate minerals, Magnesium minerals, so understanding it makes those chapters shorter.
In everyday life: Look for Motukoreaite 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 Motukoreaite in 20 minutes

Read the reference excerpt below once, without taking notes.
Close the page and write down what Motukoreaite 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 Motukoreaite out loud to somebody else — or to Teacher Smith in the lgStudy chat.

Frequently asked questions

What is Motukoreaite in simple terms?

Motukoreaite is a mineral with formula Mg6Al3(OH)18[Na(H2O)6](SO4)2·6H2O (possibly more than one species). The mineral is named for Motukorea, the island in New Zealand where it was discovered.

Why does Motukoreaite 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 Motukoreaite?

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 Motukoreaite.