earth science

Massive sulfide deposits

Massive sulfide deposits 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 Massive sulfide deposits rather than just read about it. In short: Massive sulfide deposits are ore deposits that have significant stratiform ore bodies consisting mainly of sulfide minerals. Most massive sulfide ore deposits have other portions that are not massive, including stringer or feeder zones beneath the massive parts that mostly consist of crosscutting veins and veinlets of sulfides in a matrix of pervasively altered host rock and gangue.

Key takeaways

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

Reference excerpt

Massive sulfide deposits are ore deposits that have significant stratiform ore bodies consisting mainly of sulfide minerals. Most massive sulfide ore deposits have other portions that are not massive, including stringer or feeder zones beneath the massive parts that mostly consist of crosscutting veins and veinlets of sulfides in a matrix of pervasively altered host rock and gangue. The term "massive sulfide" is mainly applied to the following classes of ore deposits:

Volcanogenic massive sulfide ore deposits (VMS), also called volcanic-hosted massive sulfide deposits (VHMS) Sedimentary exhalative deposits (SEDEX), also called sediment-hosted massive sulfide deposits The main sulfide minerals occurring in both classes of massive sulfide ores are pyrite and/or pyrrhotite and variable amounts of sphalerite, galena, and chalcopyrite. The term "massive sulfide deposit" became popular in the 1960s with the discovery of seafloor massive sulfide deposits that were recognized as modern equivalents of ancient volcanic-hosted massive sulfide ore deposits (VHMS or VMS). Subsequently, the term was also widely used since the 1970s for sediment-hosted ore deposits when it was realized that sediment-hosted massive sulfide (SHMS) Zn-Pb deposits could be formed from ascending and eventually venting brines that are geochemically similar to those that form MVT deposits. The limit of what is "massive sulfide" has changed with time. One of the original definitions (1976) stated that the "term massive refers to mineralization composed of greater than 60% sulfides". This limit was kept in a comprehensive definition of 1981: "Massive sulfide deposits are strata-bound and in part stratiform accumulations of sulfide minerals which are normally composed of at least 60% sulfide minerals in their stratiform portions. The stratiform portion may comprise up to 100% of the total sulfide present, but many deposits have a substantial component of discordant vein-type sulfide mineralization, the stringer zone, mainly in the footwall strata." In recent times a limit of 40% sulfides has been more common.

References

Worked examples

Example 1 — a first encounter with Massive sulfide deposits

Start with the simplest possible case. Write down what Massive sulfide deposits 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 Massive sulfide deposits 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 Massive sulfide deposits 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 Massive sulfide deposits

In research: Massive sulfide deposits 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 Massive sulfide deposits 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: Massive sulfide deposits is common in secondary-school and first-year university syllabi. It links to neighbouring topics Economic geology, Ore deposits, so understanding it makes those chapters shorter.
In everyday life: Look for Massive sulfide deposits 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 Massive sulfide deposits in 20 minutes

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

Frequently asked questions

What is Massive sulfide deposits in simple terms?

Why does Massive sulfide deposits 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 Massive sulfide deposits?

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 Massive sulfide deposits.