earth science

Fülöppite

Fülöppite 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 Fülöppite rather than just read about it. In short: Fülöppite is a rare member of the plagionite group, comprising heteromorphite Pb7Sb8S19, plagionite Pb5Sb8S17 and semseyite Pb9Sb8S21. It was named in 1929 for Dr.

Key takeaways

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

Reference excerpt

Fülöppite is a rare member of the plagionite group, comprising heteromorphite Pb7Sb8S19, plagionite Pb5Sb8S17 and semseyite Pb9Sb8S21. It was named in 1929 for Dr. Béla Fülöpp (1863–1938), a Hungarian lawyer, statesman and mineral collector.

Structure Fülöppite forms a homologous series with other members of the plagionite group. The structures of these minerals differ by the thickness of a galena sheet which occurs in all of them. Fülöppite has the thinnest such sheet.

Crystallography There are four formula units (Z = 4) per unit cell, and it has sides of lengths a = 13.44 Å, b = 11.73 Å and c = 16.93 Å, with the angle between a and c being β = 94.7°. Crystals are short prismatic parallel to [201], up to 3 mm long, or pyramidal. They are striated on {100} parallel to [010] and on {112} parallel to [110]. Forms which have been observed include (001), (100), (101), (112), (111), (223), (111) and (221). Curved crystals are common. The numbers in brackets are Miller indices.

Appearance The crystals are short prismatic and pyramidal, with a lead-grey colour that may tarnish to steel-blue or bronze-white. The streak is reddish grey. The crystals are opaque, with a metallic lustre.

Physical properties Fülöppite is opaque. A petrographic microscope can be used to examine opaque materials under reflected polarised light. Under these conditions the mineral shows moderate anisotropism, changing colour from blue-green to red-brown. The reflectivity of a surface is the percentage of incident light energy that is reflected. It varies with the medium above the surface, such as air or oil, and with the wavelength of the incident light. The reflectivity of fülöppite in air for light of wavelength 540 nm is 31.9% to 40.1%. The mineral is brittle with an uneven fracture. It is soft, with a Moh's hardness of only 2+1⁄2, and heavy, with specific gravity 5.2. It melts easily in an open tube yielding sulphur fumes and a deposit of Sb2S2. It is not attacked by concentrated hydrochloric acid.

Occurrence The type locality is the Dealul Crucii Adit, Baia Mare, Maramureș County, Romania, and the type material is kept at the Natural History Museum, London, England, reference 1929,248. It is of hydrothermal origin and associated with zinkenite, semseyite, fizélyite, andorite, freieslebenite, geocronite, boulangerite, jamesonite, cinnabar, sphalerite, marcasite, quartz and dolomite. Fülöppite was first reported in Britain from Wet Swine Gill, Caldbeck Fells, Cumbria. It was described as dark grey metallic patches of fibrous crystals accompanying stibnite. Subsequently, rare dark red resinous to submetallic crystals associated with stibnite were identified as being close to fülöppite in composition.

References

Illustrations

Worked examples

Example 1 — a first encounter with Fülöppite

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

In research: Fülöppite 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 Fülöppite 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: Fülöppite is common in secondary-school and first-year university syllabi. It links to neighbouring topics Lead minerals, Minerals in space group 15, Monoclinic minerals, so understanding it makes those chapters shorter.
In everyday life: Look for Fülöppite 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 Fülöppite in 20 minutes

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

Frequently asked questions

What is Fülöppite in simple terms?

Fülöppite is a rare member of the plagionite group, comprising heteromorphite Pb7Sb8S19, plagionite Pb5Sb8S17 and semseyite Pb9Sb8S21. It was named in 1929 for Dr.

Why does Fülöppite 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 Fülöppite?

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 Fülöppite.