earth science

Heazlewoodite

Heazlewoodite 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 Heazlewoodite rather than just read about it. In short: Heazlewoodite, Ni3S2, is a rare sulfur-poor nickel sulfide mineral found in serpentinitized dunite. It occurs as disseminations and masses of opaque, metallic light bronze to brassy yellow grains which crystallize in the trigonal crystal system.

Key takeaways

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

Reference excerpt

Heazlewoodite, Ni3S2, is a rare sulfur-poor nickel sulfide mineral found in serpentinitized dunite. It occurs as disseminations and masses of opaque, metallic light bronze to brassy yellow grains which crystallize in the trigonal crystal system. It has a hardness of 4, a specific gravity of 5.82. Heazlewoodite was first described in 1896 from Heazlewood, Tasmania, Australia.

Paragenesis Heazlewoodite is formed within terrestrial rocks by metamorphism of peridotite and dunite via a process of nucleation. Heazlewoodite is the least sulfur saturated of nickel sulfide minerals and is only formed via metamorphic exsolution of sulfur from the lattice of metamorphic olivine. Heazlewoodite 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 Mg2+). 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. In this environment, nickel sulfide mineralogy converts to the lowest-sulfur state available, which is heazlewoodite.

Occurrence Heazlewoodite is known from few ultramafic intrusions within terrestrial rocks. The Honeymoon Well ultramafic intrusive, Western Australia is known to contain heazlewoodite-millerite sulfide assemblages within serpentinized olivine adcumulate dunite, formed from the metamorphic process. The mineral is also reported, again in association with millerite, from the ultramafic rocks of New Caledonia. This mineral has been found in meteorites including irons and CV carbonaceous chondrites.

See also Dunite or peridotite Glossary of meteoritics Metamorphism Millerite Olivine Polydymite Serpentinite Vaesite

References

Guillon J.H. and Lawrence L.J., The opaque minerals of the ultramafic rocks of New Caledonia, Mineralium Deposita, volume 8, 1973, pp. 115–126.

Illustrations

Worked examples

Example 1 — a first encounter with Heazlewoodite

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

In research: Heazlewoodite 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 Heazlewoodite 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: Heazlewoodite is common in secondary-school and first-year university syllabi. It links to neighbouring topics Meteorite minerals, Minerals in space group 155, Nickel minerals, so understanding it makes those chapters shorter.
In everyday life: Look for Heazlewoodite 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 Heazlewoodite in 20 minutes

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

Frequently asked questions

What is Heazlewoodite in simple terms?

Why does Heazlewoodite 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 Heazlewoodite?

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 Heazlewoodite.