earth science

Leifite

Leifite 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 Leifite rather than just read about it. In short: Leifite is a rare tectosilicate. Tectosilicates are built on a framework of tetrahedra with silicon or aluminium at the centre and oxygen at the vertices; they include feldspars and zeolites, but leifite does not belong in either of these categories.

Key takeaways

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

Reference excerpt

Leifite is a rare tectosilicate. Tectosilicates are built on a framework of tetrahedra with silicon or aluminium at the centre and oxygen at the vertices; they include feldspars and zeolites, but leifite does not belong in either of these categories. It is a member of the leifite group, which includes telyushenkoite (Cs,Na,K)Na6(Be2Al3Si15O39) and eirikite KNa6Be2(Si15Al3)O39F2). Leifite was discovered in 1915, and named after Leif Ericson who was a Norse explorer who lived around 1000 AD, and was probably the first European to land in North America, nearly 500 years before Christopher Columbus. Eirikite was named in 2007 after Eirik Raude, or Erik the Red, (950–1003), who discovered Greenland and who was the father of Leif Ericson. The third mineral in the group, telyushenkoite, was discovered in 2001. It was not named after any of Leif Ericson's family members, but after a professor of geology in Turkmenistan.

Structure Leifite is a trigonal mineral, class 3 2/m, space group P3m1. There are 3 formula units in the unit cell (Z = 3), and cell dimensions are 14.4 Å in the a direction and 4.9 Å in the c direction. It contains OH groups, but no water of crystallization as was previously assumed. Tetrahedrons of silicon or aluminium atoms surrounded by four oxygen atoms link to form six-membered rings stacked along the c direction to form channels, similar to those in zeolites.

Appearance Leifite is generally white or colourless, with a white streak and a silky or vitreous lustre. It occurs as fine needles making up radiating aggregates and rosettes. Individual crystals are deeply striated hexagonal prisms that are transparent to translucent.

Physical Properties The mineral is hard, with Mohs hardness 6, the same as that of feldspar, and specific gravity 2.6, again like the feldspars. It is brittle, with an uneven to splintery fracture.

Optical Properties Leifite is uniaxial(+) with refractive indices nω = 1.516 and nε = 1.520. The maximum birefringence δ = 0. 011. Leifite is not luminescent.

Occurrence The type locality is the Narsaarsuk pegmatite on the Narsaarsuk Plateau, Igaliku, Narsaq, Kujalleq, Greenland and type material is kept at the University of Copenhagen, Denmark, and at the National Museum of Natural History in Washington DC, US. Leifite occurs in cavities in alkali-pegmatite veins. At Mont Saint-Hilaire it occurs as crystals up to 5 cm long and as disk-shaped aggregates and radially fibrous spheres associated with albite, natrolite, serandite and catapleite. In Greenland it occurs in a pegmatite with microcline, calcite, zinnwaldite and acmite. In Russia it occurs in the Lovozero Massif associated with albite and natrolite. In Norway it occurs in a nepheline syenite pegmatite on the south eastern part of the island of Vesle Aroya in the Langesundsfjord District, Oslo Region, as white to colourless fibrous masses and radiating bundles.

References

Illustrations

Worked examples

Example 1 — a first encounter with Leifite

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

In research: Leifite 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 Leifite 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: Leifite is common in secondary-school and first-year university syllabi. It links to neighbouring topics Minerals in space group 164, Silicate minerals, Trigonal minerals, so understanding it makes those chapters shorter.
In everyday life: Look for Leifite 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 Leifite in 20 minutes

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

Frequently asked questions

What is Leifite in simple terms?

Why does Leifite 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 Leifite?

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 Leifite.