earth science

Periclase

Periclase 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 Periclase rather than just read about it. In short: Periclase is a magnesium mineral that occurs naturally in contact metamorphic rocks and is a major component of most basic refractory bricks. It is a cubic form of magnesium oxide (MgO).

Key takeaways

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

Reference excerpt

Periclase is a magnesium mineral that occurs naturally in contact metamorphic rocks and is a major component of most basic refractory bricks. It is a cubic form of magnesium oxide (MgO). In nature it usually forms a solid solution with wüstite (FeO) and is then referred to as ferropericlase or magnesiowüstite. It was first described in 1840 and named from the Greek περικλάω (to break around) in allusion to its cleavage. The type locality is Monte Somma, Somma-Vesuvius Complex, Naples Province, Campania, Italy. The old term for the mineral is magnesia. Stones from the Magnesia region in ancient Anatolia contained both magnesium oxide and hydrated magnesium carbonate as well as iron oxides (such as magnetite). Thus these stones, called Stones from Magnesia in antiquity, with their unusual magnetic properties were the reason the terms magnet and magnetism were coined. Periclase is usually found in marble produced by metamorphism of dolomitic limestones. It readily alters to brucite under near surface conditions. In addition to its type locality, it is reported from Predazzo, Trentino, Italy; Carlingford, County Louth, Ireland; Broadford, Skye and the island of Muck, Scotland; León, Spain; the Bellerberg Volcano, Eifel district, Germany; Nordmark and Långban, Varmland, Sweden; and Kopeysk, southern Ural Mountains, Russia. In the US it occurs at the Crestmore quarry, Riverside County, California; Tombstone, Arizona; Gabbs district, Nye County, Nevada. In Canada, it occurs at Oka, Quebec and in Australia, west of Cowell, Eyre Peninsula, South Australia. The crystal structure of periclase corresponds to that of halite and has been studied extensively due to its simplicity. As a consequence, the physical properties of periclase are well known, which makes the mineral a popular standard in experimental work. The mineral has been shown to remain stable at pressures up to at least 360 GPa.

Mantle occurrence Ferropericlase (Mg,Fe)O makes up about 20% of the volume of the lower mantle of the Earth, which makes it the second most abundant mineral phase in that region after silicate perovskite (Mg,Fe)SiO3; it also is the major host for iron in the lower mantle. At the bottom of the transition zone of the mantle, the reaction

γ–(Mg,Fe)2[SiO4] ↔ (Mg,Fe)[SiO3] + (Mg,Fe)O transforms γ-olivine into a mixture of perovskite and ferropericlase and vice versa. In the literature, this mineral phase of the lower mantle is also often called magnesiowüstite.

References

Illustrations

Worked examples

Example 1 — a first encounter with Periclase

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

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

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

Frequently asked questions

What is Periclase in simple terms?

Periclase is a magnesium mineral that occurs naturally in contact metamorphic rocks and is a major component of most basic refractory bricks. It is a cubic form of magnesium oxide (MgO).

Why does Periclase 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 Periclase?

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 Periclase.