earth science

Merrillite

Merrillite 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 Merrillite rather than just read about it. In short: Merrillite is a calcium phosphate mineral with the chemical formula Ca9NaMg(PO4)7. It is an anhydrous, sodium-rich member of the merrillite group of minerals.

Key takeaways

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

Reference excerpt

Merrillite is a calcium phosphate mineral with the chemical formula Ca9NaMg(PO4)7. It is an anhydrous, sodium-rich member of the merrillite group of minerals.

Mineral species, sub-group and group Merrillite is a distinct mineral species but it also gives its name to a set of similar minerals, which together form the merrillite sub-group of minerals. The merrillite sub-group and the whitlockite sub-group together form the merrillite group of minerals.

Merrillite Group Merrillite Sub-group Ferromerrillite Keplerite Matyhite Merrillite Whitlockite Sub-group Hedegaardite Strontiowhitlockite Whitlockite Wopmayite In September 2022 the discovery of another merrillite group mineral, changesite–(Y), was announced, but, as of September 2022, it is not yet clear where this new mineral sits in the merrillite group hierarchy.

Discovery and naming Merrillite is named after George P. Merrill (1854–1929) of the Smithsonian Institution. In 1915, Merrill had described the mineral from four meteorites: Alfianello, Dhurmsala, Pultusk and Rich Mountain. Merrillite has also been reported from the Renchen meteorite (a well-documented fall that occurred on 10 July 2018 at 21:29 UTC in southwestern Germany), occurring in the form of a merrillite–apatite aggregate. However, it was not until 1975 that it was recognized as distinct from whitlockite by the International Mineralogical Association.

Occurrence Merrillite is a very important constituent of extraterrestrial rocks. It occurs in lunar rocks and in meteorites (for example, pallasites and martian meteorites). In 2022, for the first time, merrillite was found in a terrestrial environment, as an inclusion in lower-mantle diamonds from Sorriso River, Juína, Brazil.

References

Illustrations

Worked examples

Example 1 — a first encounter with Merrillite

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

In research: Merrillite 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 Merrillite 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: Merrillite is common in secondary-school and first-year university syllabi. It links to neighbouring topics Meteorite minerals, Phosphate mineral stubs, Phosphate minerals, so understanding it makes those chapters shorter.
In everyday life: Look for Merrillite 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 Merrillite in 20 minutes

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

Frequently asked questions

What is Merrillite in simple terms?

Merrillite is a calcium phosphate mineral with the chemical formula Ca9NaMg(PO4)7. It is an anhydrous, sodium-rich member of the merrillite group of minerals.

Why does Merrillite 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 Merrillite?

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 Merrillite.