earth science

Sewardite

Sewardite 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 Sewardite rather than just read about it. In short: Sewardite is a rare arsenate mineral with formula of CaFe3+2(AsO4)2(OH)2. Sewardite was discovered in 1982 and named for the mineralogist, Terry M.

Key takeaways

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

Reference excerpt

Sewardite is a rare arsenate mineral with formula of CaFe3+2(AsO4)2(OH)2. Sewardite was discovered in 1982 and named for the mineralogist, Terry M. Seward (born 1940), a professor of geochemistry in Zürich, Switzerland.

Properties Sewardite is orthorhombic, which means that it contains three axes of unequal length, a, b, and c, which are all at 90° to one another. Its class structure is mmm (2/m 2/m 2/m) – dipyramidal. Sewardite can form platy-to-compact anhedral-to-subhedral masses up to 0.3 mm in size. In terms of its optical properties, sewardite is weakly anisotropic, which means the velocity of light varies depending on the direction through the mineral. Its color in plane-polarized light is dark red, and it does not exhibit pleochroism, which means it does not appear to be a different color when observed at different angles under a polarizing petrographic microscope. Sewardite illustrates weak birefringence because it is weakly anisotropic.

Occurrence Sewardite has only been found at three locations, in the Tsumeb mine in Tsumeb, Namibia, Mina Ojuela, Mapimi, Durango, Mexico, and La Mur, Las Animas mine, Sonora, Mexico. At the site in Durango, Mexico, it occurs as a dark, reddish spherules and rosettes of very thin, flaky crystals. This newly discovered mineral (confirmed as a species in 1998) has been determined as rare, since only 1–2 mg of it were found in the Tsumeb mine.

References

Worked examples

Example 1 — a first encounter with Sewardite

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

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

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

Frequently asked questions

What is Sewardite in simple terms?

Sewardite is a rare arsenate mineral with formula of CaFe3+2(AsO4)2(OH)2. Sewardite was discovered in 1982 and named for the mineralogist, Terry M.

Why does Sewardite 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 Sewardite?

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 Sewardite.