earth science

Riebeckite

Riebeckite 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 Riebeckite rather than just read about it. In short: Riebeckite is a sodium-rich member of the amphibole group of silicate minerals. It has chemical formula Na2(Fe2+3Fe3+2)Si8O22(OH)2.

Key takeaways

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

Reference excerpt

Riebeckite is a sodium-rich member of the amphibole group of silicate minerals. It has chemical formula Na2(Fe2+3Fe3+2)Si8O22(OH)2. It forms a solid solution series with magnesioriebeckite, where Mg substitutes for Fe2+. It crystallizes in the monoclinic system, usually as long prismatic crystals showing a diamond-shaped cross section, but also in fibrous, bladed, acicular, columnar, and radiating forms. Its Mohs hardness is 5.0–6.0, and its specific gravity is 3.0–3.4. It has perfect cleavage in two directions in the shape of a rhombus, while its fracture is uneven and splintery. It is often translucent to nearly opaque.

Name and discovery Riebeckite was first described in 1888 for an occurrence on Socotra Island, Aden Governorate, Yemen, and named for German explorer Emil Riebeck (1853–1885).

Occurrence Riebeckite typically forms dark-blue elongated to fibrous crystals in highly alkali granites andsyenites. It forms more rarely in felsic volcanics, granite pegmatites and schist. It occurs in banded iron formations as the asbestiform variety crocidolite (blue asbestos). It occurs in association with aegirine, nepheline, albite, arfvedsonite in igneous rocks; with tremolite, ferro-actinolite in metamorphic rocks; and with grunerite, magnetite, hematite, stilpnomelane, ankerite, siderite, calcite, chalcedonic quartz in iron formations.

Riebeckite granite The riebeckite granite known as ailsite, found on the island of Ailsa Craig in western Scotland, is prized for its use in the manufacture of curling stones. Riebeckite granite was used for the facing stones of the Canton Viaduct from Moyles Quarry (a.k.a. Canton Viaduct Quarry), now part of Borderland State Park in the US state of Massachusetts. The commonwealth's name is taken from an Algonquian word for the Great Blue Hill, whose color is due to this form of granite.

Crocidolite (fibrous riebeckite)

The fibrous forms of riebeckite are known as crocidolite and are one of the six recognised types of asbestos. Often referred to as blue asbestos, it is considered the most hazardous. The association between blue asbestos and mesothelioma was established by J. C. Wagner, C. A. Sleggs, and P. Marchand by 1960. Crocidolite asbestos was mined in South Africa, Bolivia, and Wittenoom, Western Australia. Bolivian crocidolite was used in approximately 13 billion Kent Micronite cigarette filters, manufactured from March 1952 until at least May 1956 by the Lorillard Tobacco Company (now part of the R. J. Reynolds Tobacco Company). Blue asbestos was also used to similar effect, and hazard, in early gas masks.

See also List of minerals List of minerals named after people

References

External links

Chisholm, Hugh, ed. (1911). "Crocidolite" . Encyclopædia Britannica. Vol. 7 (11th ed.). Cambridge University Press. p. 477.

Illustrations

Worked examples

Example 1 — a first encounter with Riebeckite

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

In research: Riebeckite 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 Riebeckite 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: Riebeckite is common in secondary-school and first-year university syllabi. It links to neighbouring topics Amphibole group, Asbestos, Iron(II,III) minerals, so understanding it makes those chapters shorter.
In everyday life: Look for Riebeckite 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 Riebeckite in 20 minutes

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

Frequently asked questions

What is Riebeckite in simple terms?

Riebeckite is a sodium-rich member of the amphibole group of silicate minerals. It has chemical formula Na2(Fe2+3Fe3+2)Si8O22(OH)2.

Why does Riebeckite 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 Riebeckite?

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 Riebeckite.