earth science

Spaltiite

Spaltiite 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 Spaltiite rather than just read about it. In short: Spaltiite is a rare thallium sulfosalt mineral with the ideal chemical formula Tl2Cu2As2S5. It was discovered on a waste dump of the Lengenbach quarry in the Binn Valley (Binntal), Canton Valais, Switzerland, a locality famous for producing an unusually large number of rare thallium- and arsenic-bearing sulfosalt minerals.

Key takeaways

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

Reference excerpt

Spaltiite is a rare thallium sulfosalt mineral with the ideal chemical formula Tl2Cu2As2S5. It was discovered on a waste dump of the Lengenbach quarry in the Binn Valley (Binntal), Canton Valais, Switzerland, a locality famous for producing an unusually large number of rare thallium- and arsenic-bearing sulfosalt minerals. Spaltiite was approved as a valid mineral species by the International Mineralogical Association's Commission on New Minerals, Nomenclature and Classification (IMA-CNMNC) in 2014, but a full scientific description of the species, including its crystal structure, was not published until 2026.

Occurrence and discovery The only known specimen of spaltiite, containing three crystals of the mineral, was recovered from a dump at the Lengenbach quarry, hosted in a small piece of pure white dolomite of Triassic age belonging to the Penninic Monte Leone Nappe. The Lengenbach locality has been mined and collected for more than 200 years and is the type locality for over 50 mineral species, with an especially large number of rare thallium- and arsenic-bearing sulfosalts. On the type specimen, spaltiite occurs together with pyrite, drechslerite and hatchite.

Name and classification The name spaltiite derives from the nickname "spalti", used informally by researchers during laboratory study of the mineral, in reference to its extremely well-developed cleavage; the name is ultimately derived from the German verb spalten, meaning "to split". The species and its name were approved by the IMA-CNMNC under proposal number IMA2014-012. The formal description of spaltiite was authored by Stefan Graeser, Dan Topa, Herta S. Effenberger, Emil Makovicky, Werner H. Paar and George Dincă, and published in the European Journal of Mineralogy in 2026. The holotype specimen is held in the collections of the Natural History Museum Vienna (catalogue no. N 9528).

Physical and chemical properties Spaltiite forms greyish to black, extremely soft euhedral crystals with a long prismatic to lath-like habit, typically around 2 mm in length but only about 0.2 mm thick. It has a Mohs hardness of 1.5–2, with measured Vickers microhardness (VHN15) ranging from 30 to 65 kg/mm2 (mean 47 kg/mm2). The mineral has a perfect cleavage parallel to {100}, which produces minute, plastic slabs. Electron-microprobe analyses of the type material gave an empirical formula of approximately Tl1.94Cu2.04Ag0.01As1.95Sb0.03S5.03, close to the ideal formula Tl2Cu2As2S5. Spaltiite is monoclinic, crystallizing in space group P21/c, with unit-cell parameters a = 15.791(8) Å, b = 10.000(5) Å, c = 6.323(3) Å, β = 99.25(8)°, and a unit-cell volume of 985.5(8) Å3. Its crystal structure has been described as having a pronounced layered atomic arrangement, with two polar Cu–As layers related to one another by inversion symmetry.

See also List of minerals recognized by the International Mineralogical Association

References

attribution: contains text copied from https://doi.org/10.5194/ejm-38-27-2026 which was published under a CC-BY-4.0 license

Worked examples

Example 1 — a first encounter with Spaltiite

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

In research: Spaltiite 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 Spaltiite 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: Spaltiite is common in secondary-school and first-year university syllabi. It links to neighbouring topics Arsenic minerals, Copper minerals, Minerals described in 2014, so understanding it makes those chapters shorter.
In everyday life: Look for Spaltiite 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 Spaltiite in 20 minutes

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

Frequently asked questions

What is Spaltiite in simple terms?

Why does Spaltiite 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 Spaltiite?

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 Spaltiite.