earth science

Natrolite

Natrolite 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 Natrolite rather than just read about it. In short: Natrolite is a tectosilicate mineral species belonging to the zeolite group. It is a hydrated sodium and aluminium silicate with the formula Na2Al2Si3O10·2H2O.

Key takeaways

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

Reference excerpt

Natrolite is a tectosilicate mineral species belonging to the zeolite group. It is a hydrated sodium and aluminium silicate with the formula Na2Al2Si3O10·2H2O. The type locality is Hohentwiel, Hegau, Germany.

It was named natrolite by Martin Heinrich Klaproth in 1803. The name is derived from natron (νατρών), the Greek word for soda, in reference to the sodium content, and lithos (λίθος), meaning stone. Needle stone or needle-zeolite are other informal names, alluding to the common acicular habit of the crystals, which are often very slender and are aggregated in divergent tufts. The crystals are frequently epitaxial overgrowths of natrolite, mesolite, and gonnardite in various orders.

Properties Larger crystals most commonly have the form of a square prism terminated by a low pyramid, the prism angle being nearly a right angle. The crystals are tetragonal in appearance, though actually orthorhombic. There are perfect cleavages parallel to the faces of the prism. The mineral also often occurs in compact fibrous aggregates, the fibers having a divergent or radial arrangement. Natrolite is readily distinguished from other fibrous zeolites by its optical characteristics. Between crossed nicols the fibers extinguish parallel to their length, and they do not show an optic figure in convergent polarized light. Natrolite is usually white or colorless, but sometimes reddish or yellowish. The luster is vitreous, or, in finely fibrous specimens, silky. The specific gravity of natrolite is 2.2, and its hardness is 5.5. The mineral is readily fusible, melting in a candle-flame to which it imparts a yellow color owing to the presence of sodium. It is decomposed by hydrochloric acid with separation of gelatinous silica.

Environment Natrolite occurs with other zeolites in the amygdaloidal cavities of basaltic igneous rocks. It is also common in nepheline syenites.

Notable localities Excellent specimens of diverging groups of white prismatic crystals are found in compact basalt at the Puy-deMarman, Puy-de-Dôme, France. Huge crystals have been found on the Kola Peninsula, Russia (30 cm by 13 cm). The walls of cavities in the basalt of the Giants Causeway, in County Antrim, are frequently encrusted with slender needles of natrolite, and similar material is found abundantly in the volcanic rocks (basalt and phonolite) of Salesel, Aussig and several other places in the north of Bohemia. Mont St. Hilaire, Quebec has produced large crystals associated with many rare minerals. The Bay of Fundy in Nova Scotia, New Jersey, Oregon, and British Columbia have also produced excellent specimens. Several varieties of natrolite have been distinguished: fargite is a red natrolite from Glenfarg in Perthshire; bergmannite or spreustein is an impure variety which has resulted by the alteration of other minerals, chiefly sodalite, in the augite syenite of southern Norway. Natrolite is one of the closely associated minerals with benitoite, a rare mineral with its type locality in San Benito County, California. Natrolite forms opaque white spherical inclusions within nodules of translucent green prehnite from Wave Hill, Northern Territory, Australia.

Images

Illustrations

Worked examples

Example 1 — a first encounter with Natrolite

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

In research: Natrolite 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 Natrolite 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: Natrolite is common in secondary-school and first-year university syllabi. It links to neighbouring topics Aluminium minerals, Dihydrate minerals, Luminescent minerals, so understanding it makes those chapters shorter.
In everyday life: Look for Natrolite 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 Natrolite in 20 minutes

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

Frequently asked questions

What is Natrolite in simple terms?

Natrolite is a tectosilicate mineral species belonging to the zeolite group. It is a hydrated sodium and aluminium silicate with the formula Na2Al2Si3O10·2H2O.

Why does Natrolite 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 Natrolite?

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 Natrolite.