earth science

Palygorskite

Palygorskite 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 Palygorskite rather than just read about it. In short: Palygorskite or attapulgite is a magnesium aluminium phyllosilicate with the chemical formula (Mg,Al)2Si4O10(OH)·4(H2O) that occurs in a type of clay soil common to the Southeastern United States. It is one of the types of fuller's earth and commonly occurs as a fibrous clay mineral.

Key takeaways

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

Reference excerpt

Palygorskite or attapulgite is a magnesium aluminium phyllosilicate with the chemical formula (Mg,Al)2Si4O10(OH)·4(H2O) that occurs in a type of clay soil common to the Southeastern United States. It is one of the types of fuller's earth and commonly occurs as a fibrous clay mineral. Some smaller deposits of this mineral can be found in Mexico, where its use is tied to the manufacture of Maya blue in pre-Columbian times. Unlike layered phyllosilicates such as smectites, palygorskite has a chain-like crystal structure (ribbons) consisting of continuous tetrahedral silica chains linked to octahedral sheets of magnesium and aluminum, each ribbon being linked to the next by inversion of SiO4 tetrahedra along a set of Si-O-Si bonds. This structural feature contributes to many of its peculiar physicochemical properties.

Crystal structure The crystal structure of palygorskite consists of continuous tetrahedral silica chains linked to octahedral sheets of magnesium and aluminum. Periodic inversion of the tetrahedral sheets produces elongated channels running parallel to the crystallographic axis. Water in palygorskite occurs in several forms, including adsorbed surface water, channel (zeolitic) water located within the channels, and structurally bound water associated with octahedral cations. These different forms of water are released at distinct temperature ranges during heating and influence the thermal stability and physicochemical characteristics of the mineral. Palygorskite belongs to the palygorskite–sepiolite group of fibrous phyllosilicates. Minerals in this group share a chain-like crystal structure composed of continuous tetrahedral silica chains linked to discontinuous octahedral sheets. Sepiolite is structurally similar but contains wider structural channels and exhibits a higher magnesium and lower aluminum content.

Name Palygorskite was first described in 1862 for a deposit at Palygorskaya on the Popovka River, Middle Urals, Permskaya Oblast, Russia. The synonym attapulgite is derived from the U.S. town of Attapulgus, in the extreme southwest corner of the state of Georgia, where the mineral is abundant and surface-mined. In modern mineralogical classification the term palygorskite is preferred by the Commission on New Minerals, Nomenclature and Classification (CNMNC) of the International Mineralogical Association (IMA), whereas the term attapulgite remains widely used in industrial and commercial contexts.

Origin Five processes for the genesis of palygorskite were discussed in the older literature:

Formation under arid conditions, Formation connected with the weathering of basalt, Hydrothermal genesis, Synsedimentary (during sedimentary deposition) authigenesis, Postsedimentary (following sedimentary deposition) formation. Palygorskite typically forms in shallow lacustrine, fluvial, palustrine or pedogenic environments. Its formation is enhanced by semi-arid conditions characterized by high evaporation rates and alkaline waters enriched in magnesium and silica. These conditions are associated with geochemical redistribution of Mg, Si and Al under mildly alkaline conditions and crystallization from solutions with relatively high ionic strength. In some cases, palygorskite may also form through transformation of pre-existing Mg–Fe smectites, a process sometimes described as a “heritage” or transformation model.

Mining and usage

Global deposits Important palygorskite deposits occur in several parts of the world, including the southeastern United States (notably Georgia and Florida), Senegal, China, India, South Africa, Australia, and Greece. These deposits are of considerable economic importance due to the wide range of industrial, environmental, agricultural, construction, medical and consumer applications of palygorskite.

Mineral deposit in the US Two companies are involved in the industrial extraction and processing of gellant-grade attapulgite clay within the same Attapulgus deposit: Active Minerals International, LLC, and BASF Corp. In 2008, BASF acquired the assets of Zemex Attapulgite, leaving only two gellant-grade producers. Active Minerals operates a dedicated factory to produce the patented product Actigel 208 and built a new state-of-the-art production process in early 2009 involving portable plant processing at the mine site.

Palygorskite deposits in Greece In Greece, significant palygorskite deposits occur in the Ventzia Basin in the regional unit of Grevena, West Macedonia. The basin is a post-Alpine intramontane depression formed during the Upper Pliocene–Lower Pleistocene. The geological environment was characterized as fluvial and palustrine where semi-arid conditions led to high evaporation rates and alkaline waters enriched in silica and magnesium. Silica and magnesium derived from the weathering of ultramafic and mafic rocks of the Vourinos ophiolite complex and aluminum from mafic rocks and rocks from the Tsotyli Formation contributed to conditions favourable for the formation of fibrous clay minerals such as palygorskite. Several individual deposits occur within the basin, showing variations in the palygorskite-to-smectite ratio, porosity, associated mineral phases and chemical composition. These differences influence the physicochemical properties of the material and its suitability for different industrial applications. Industrial extraction and processing of palygorskite from deposits in the Ventzia Basin is carried out by Geohellas S.A..

Properties

… excerpt ends here. Continue reading the full article.

Illustrations

Worked examples

Example 1 — a first encounter with Palygorskite

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

In research: Palygorskite 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 Palygorskite 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: Palygorskite is common in secondary-school and first-year university syllabi. It links to neighbouring topics Antidiarrhoeals, Clay minerals group, Magnesium minerals, so understanding it makes those chapters shorter.
In everyday life: Look for Palygorskite 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 Palygorskite in 20 minutes

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

Frequently asked questions

What is Palygorskite in simple terms?

Why does Palygorskite 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 Palygorskite?

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 Palygorskite.