earth science

Pimelite

Pimelite 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 Pimelite rather than just read about it. In short: Pimelite was discredited as a mineral species by the International Mineralogical Association (IMA) in 2006, in an article which suggests that "pimelite" specimens are probably willemseite (which is approved), or kerolite (which is also discredited). This was a mass discreditation, and not based on any re-examination of the type material (assuming any exists).

Key takeaways

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

Reference excerpt

Pimelite was discredited as a mineral species by the International Mineralogical Association (IMA) in 2006, in an article which suggests that "pimelite" specimens are probably willemseite (which is approved), or kerolite (which is also discredited). This was a mass discreditation, and not based on any re-examination of the type material (assuming any exists). Nevertheless, a considerable number of papers have been written, verifying that pimelite is a nickel-dominant smectite. It is always possible to redefine a mineral wrongly discredited. The mineral was erroneously assumed to be a nickel-rich talc in a paper published in the American Mineralogist in 1979, but it had already been determined to be a smectite as early as 1938, and this was confirmed in another article in the American Mineralogist in 1966. Both nickel-bearing talc and nickel dominant smectite occur at the type locality, Szklary, Ząbkowice County, Lower Silesia, Poland.

Mineral group According to the literature pimelite belongs to the smectite group, trioctahedral subgroup. "Smectite" is the name of a group of minerals, not the name of a mineral species. Subgroup members:

hectorite (IMA questionable status) Na0.3(Mg,Li)3Si4O10(OH)2 pimelite (IMA discredited) Ni3Si4O10(OH)2·4H2O saponite (Ca,Na)0.3(Mg,Fe2+)3(Si,Al)4O10(OH)2·4H2O sauconite Na0.3Zn3(Si,Al)4O10(OH)2·4H2O stevensite (IMA questionable status) (Ca0.5,Na)0.33(Mg,Fe2+)3Si4O10(OH)2·n(H2O) yakhontovite (Ca,Na,K)0.2(Cu,Fe,Mg)2Si4O10(OH)2·3H2O zincsilite Zn3Si4O10(OH)2·4H2O Smectite group minerals are phyllosilicate clay minerals. Pimelite apparently constitutes part of the mixtures called garnierite or noumeite, and it could form a series with stevensite or saponite.

Discovery Pimelite was discovered in 1788 by Martin Heinrich Klaproth, and renamed in 1800 by Dietrich Ludwig Gustav Karsten (de:Dietrich Ludwig Gustav Karsten) from the Greek word for fat, in allusion to the appearance.

Structure It belongs to the hexagonal crystal system, but the crystal class is unknown. As with all phyllosilicates, the basic structural element is a triple layer, called a t-o-t layer, where "t" stands for a tetrahedral sheet and "o" stands for an octahedral sheet. The tetrahedral sheets comprise (Si,Al)O4 tetrahedra, linked together in nearly hexagonal rings. Three of the oxygens in each tetrahedron form links to other tetrahedra in the sheet, and the fourth oxygen, the apical oxygen, points away from the sheet. The apical oxygens of one tetahedral sheet face the apical oxygens of the other tetrahedral sheet, forming octahedral sites between the sheets, and this is the octahedral "o" layer. The octahedral sites may be fully occupied by divalent cations, producing trioctahedral layers, where each O or OH ion is surrounded by 3 divalent cations. Alternatively the octahedral sites may be 2/3 occupied by trivalent cations, producing dioctahedral layers, where each O or OH ion is surrounded by 2 trivalent cations. There is one formula unit per unit cell (Z = 1), and the unit cell parameters are a = 5.256 Å and c = 14.822 Å. When treated with glycol the cell expands to 17.35 Å.

Appearance Pimelite does not form visible crystals. It is fine-grained or fibrous, with the apple green color typical of nickel compounds. It is translucent, with a white streak and a waxy luster.

Optical properties It is biaxial (−) but it can appear isotropic due to its fine grain size. The refractive indices are Nx = 1.592 and Ny = 1.615. It is pleochroic, pale green, and colorless to light yellow green. It is not fluorescent.

Physical properties Pimelite breaks with an uneven to conchoidal fracture, but it shows no cleavage. It is soft with Mohs hardness 2 to 2.5, similar to that of gypsum, and its specific gravity is 2.23 to 2.98. It is neither radioactive nor magnetic. It is decomposed by acids.

Occurrence Pimelite is found in lateritic nickel ore deposits above serpentinites or dunites, frequently mixed with nickel-rich serpentine minerals or quartz. The type locality is Kosemutz, near Frankenstein, Silesia, Poland, and it has also been found in New Jersey, US. A nickel silicate hydroxide mineral was first described from Franklin, New Jersey, in 1889, but it has not been reported from the neighbouring Sterling Hill. It was originally called desaulesite, for Major de Saules, manager of the Trotter Mine at Franklin, but that name is now used for zinc-rich garnierite. In 1966 the material was shown to be identical with pimelite. Pimelite from the Trotter Shaft occurs as localized, patchy, thin crusts and dense 1 to 6 cm masses as an alteration product of nickel arsenides. It is a secondary, low-temperature mineral, associated with annabergite, fluorite, baryte and sphalerite.

References

Illustrations

Worked examples

Example 1 — a first encounter with Pimelite

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

In research: Pimelite 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 Pimelite 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: Pimelite is common in secondary-school and first-year university syllabi. It links to neighbouring topics Hexagonal minerals, Nickel minerals, Phyllosilicates, so understanding it makes those chapters shorter.
In everyday life: Look for Pimelite 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.

Affiliate

Preply — study more efficiently by working with a personal tutor. 50% off.

How to study Pimelite in 20 minutes

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

Frequently asked questions

What is Pimelite in simple terms?

Why does Pimelite 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 Pimelite?

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 Pimelite.