chemistry

Iron(II,III) sulfide

Iron(II,III) sulfide is a chemistry 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 Iron(II,III) sulfide rather than just read about it. In short: Iron(II,III) sulfide is a blue-black (sometimes pinkish) chemical compound of iron and sulfur with formula Fe3S4 or FeS·Fe2S3, which is much similar to iron(II,III) oxide. It occurs naturally as the sulfide mineral greigite and is magnetic.

Key takeaways

Iron(II,III) sulfide belongs to chemistry; place it in that map before memorising details.
Learn the definition first, then one example that makes the definition concrete.
Connect Iron(II,III) sulfide to a quantity you can measure, compute or draw — that is where exam questions come from.
Reproduce the core statement of Iron(II,III) sulfide from memory before moving on to harder problems.

Reference excerpt

Iron(II,III) sulfide is a blue-black (sometimes pinkish) chemical compound of iron and sulfur with formula Fe3S4 or FeS·Fe2S3, which is much similar to iron(II,III) oxide. It occurs naturally as the sulfide mineral greigite and is magnetic. It is a bio-mineral produced by and found in magnetotactic bacteria. It is a mixed valence compound, featuring both Fe2+ and Fe3+ centers, in 1:2 ratio.

Crystal structure The crystallographic unit cell is cubic, with space group Fd3m. The S anions form a cubic close-packed lattice, and the Fe cations occupy both tetrahedral and octahedral sites.

Magnetic and electronic properties Like the related oxide magnetite (Fe3O4), iron(II,III) sulfide is ferrimagnetic, with the spin magnetic moments of the FeIII centers in the tetrahedral sites oriented in the opposite direction as those in the octahedral sites, and a net magnetization. Both metal sites have high spin quantum numbers. The electronic structure of greigite is that of a half metal.

References

Further reading Mann, Stephen; Sparks, Nicholas H. C.; Frankel, Richard B.; Bazylinski, Dennis A.; Jannasch, Holger W. (1990). "Biomineralization of ferrimagnetic greigite (Fe3S4) and iron pyrite (FeS2) in a magnetotactic bacterium". Nature. 343 (6255): 258. Bibcode:1990Natur.343..258M. doi:10.1038/343258a0. S2CID 4351424. Roberts, A (1995). "Magnetic properties of sedimentary greigite (Fe3S4)". Earth and Planetary Science Letters. 134 (3–4): 227–236. Bibcode:1995E&PSL.134..227R. doi:10.1016/0012-821X(95)00131-U. Heywood, B. R.; Bazylinski, D. A.; Garratt-Reed, A.; Mann, S.; Frankel, R. B. (1990). "Controlled biosynthesis of greigite (Fe3S4) in magnetotactic bacteria". Naturwissenschaften. 77 (11): 536–538. Bibcode:1990NW.....77..536H. doi:10.1007/BF01139266. S2CID 28912546. Reynolds, R. L.; Tuttle, M. L.; Rice, C. A.; Fishman, N. S.; Karachewski, J. A.; Sherman, D. M. (1994). "Magnetization and geochemistry of greigite-bearing Cretaceous strata, North Slope basin, Alaska". American Journal of Science. 294 (4): 485–528. doi:10.2475/ajs.294.4.485. Snowball, Ian; Thompson, Roy (1988). "The occurrence of Greigite in sediments from Loch Lomond". Journal of Quaternary Science. 3 (2): 121–125. Bibcode:1988JQS.....3..121S. doi:10.1002/jqs.3390030203. Stanjek, H.; Fassbinder, J. W. E.; Vali, H.; Wagele, H.; Graf, W. (1994). "Evidence of biogenic greigite (ferrimagnetic Fe3S4) in soil". European Journal of Soil Science. 45 (2): 97–103. doi:10.1111/j.1365-2389.1994.tb00490.x. Hoffmann, V (1992). "Greigite (Fe3S4): magnetic properties and first domain observations". Physics of the Earth and Planetary Interiors. 70 (3–4): 288–301. Bibcode:1992PEPI...70..288H. doi:10.1016/0031-9201(92)90195-2. Fassbinder, Jörg W. E.; Stanjek, Helge (1994). "Magnetic properties of biogenic soil greigite (Fe3S4)". Geophysical Research Letters. 21 (22): 2349–2352. Bibcode:1994GeoRL..21.2349F. doi:10.1029/94GL02506.

Illustrations

Worked examples

Example 1 — a first encounter with Iron(II,III) sulfide

Start with the simplest possible case. Write down what Iron(II,III) sulfide claims or describes in one sentence, then invent the smallest concrete situation in which that sentence is true. In chemistry, 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 Iron(II,III) sulfide 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 Iron(II,III) sulfide 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 Iron(II,III) sulfide

In research: Iron(II,III) sulfide appears in chemistry 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 Iron(II,III) sulfide 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: Iron(II,III) sulfide is common in secondary-school and first-year university syllabi. It links to neighbouring topics Iron(II,III) compounds, Sulfides, so understanding it makes those chapters shorter.
In everyday life: Look for Iron(II,III) sulfide 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 Iron(II,III) sulfide in 20 minutes

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

Frequently asked questions

What is Iron(II,III) sulfide in simple terms?

Why does Iron(II,III) sulfide matter?

Because it connects several chemistry 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 Iron(II,III) sulfide?

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 Iron(II,III) sulfide.