earth science

Millerite

Millerite 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 Millerite rather than just read about it. In short: Millerite or nickel blende is a nickel sulfide mineral, NiS. It is brassy in colour and has an acicular habit, often forming radiating masses and furry aggregates.

Key takeaways

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

Reference excerpt

Millerite or nickel blende is a nickel sulfide mineral, NiS. It is brassy in colour and has an acicular habit, often forming radiating masses and furry aggregates. It can be distinguished from pentlandite by crystal habit, its duller colour, and general lack of association with pyrite or pyrrhotite.

Paragenesis Millerite is a common metamorphic mineral replacing pentlandite within serpentinite ultramafics. It is formed in this way by removal of sulfur from pentlandite or other nickeliferous sulfide minerals during metamorphism or metasomatism. Millerite is also formed from sulfur poor olivine cumulates by nucleation. Millerite is thought to form from sulfur and nickel which exist in pristine olivine in trace amounts, and which are driven out of the olivine during metamorphic processes. Magmatic olivine generally has up to ~4000 ppm Ni and up to 2500 ppm S within the crystal lattice, as contaminants and substituting for other transition metals with similar ionic radii (Fe2+ and Mn2+).

During metamorphism, sulfur and nickel within the olivine lattice are reconstituted into metamorphic sulfide minerals, chiefly millerite, during serpentinization and talc carbonate alteration. When metamorphic olivine is produced, the propensity for this mineral to resorb sulfur, and for the sulfur to be removed via the concomitant loss of volatiles from the serpentinite, tends to lower sulfur fugacity. This forms disseminated needle like millerite crystals dispersed throughout the rock mass. Millerite may be associated with heazlewoodite and is considered a transitional stage in the metamorphic production of heazlewoodite via the above process.

Economic importance Millerite, when found in enough concentration, is a very important ore of nickel because, for its mass as a sulfide mineral, it contains a higher percentage of nickel than pentlandite. This means that, for every percent of millerite, an ore contains more nickel than an equivalent percentage of pentlandite sulfide. Millerite forms an important ore constituent of the Silver Swan, Wannaway, Cliffs, Honeymoon Well, Yakabindie and Mt Keith (MKD5) orebodies. It is an accessory mineral associated with nickel laterite deposits in New Caledonia.

Occurrence

Millerite is found as a metamorphic replacement of pentlandite within the Silver Swan nickel deposit, Western Australia, and throughout the many ultramafic serpentinite bodies of the Yilgarn craton, Western Australia, generally as a replacement of metamorphosed pentlandite. There is one known occurrence of millerite in South Africa, near Pafuri in the Transvaal. The deposit has never been commercially mined. It is commonly found as radiating clusters of acicular needle-like crystals in cavities in sulfide rich limestone and dolomite or in geodes. It is also found in nickel-iron meteorites, such as CK carbonaceous chondrites. Millerite was discovered by Wilhelm Haidinger in 1845 in the coal mines of Wales. It was named for British mineralogist William Hallowes Miller. The mineral is quite rare in specimen form, and the most common source of the mineral is in the Halls Gap area of Lincoln County, Kentucky in the United States.

See also List of minerals List of minerals named after people Nickel Mines, Pennsylvania

References

External links

Mineral galleries Wisconsin minerals University of Kentucky, Kentucky Geological Survey, Sulfide Minerals

Illustrations

Worked examples

Example 1 — a first encounter with Millerite

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

In research: Millerite 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 Millerite 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: Millerite is common in secondary-school and first-year university syllabi. It links to neighbouring topics Blendes, Minerals in space group 160, Nickel minerals, so understanding it makes those chapters shorter.
In everyday life: Look for Millerite 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 Millerite in 20 minutes

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

Frequently asked questions

What is Millerite in simple terms?

Millerite or nickel blende is a nickel sulfide mineral, NiS. It is brassy in colour and has an acicular habit, often forming radiating masses and furry aggregates.

Why does Millerite 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 Millerite?

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 Millerite.