earth science

Perhamite

Perhamite 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 Perhamite rather than just read about it. In short: Perhamite is a phosphate mineral with the formula Ca3Al7(SiO4)3(PO4)4(OH)3·16.5(H2O). It occurs in rare isolated masses in amblygonite-rich pegmatite deposits throughout the world.

Key takeaways

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

Reference excerpt

Perhamite is a phosphate mineral with the formula Ca3Al7(SiO4)3(PO4)4(OH)3·16.5(H2O). It occurs in rare isolated masses in amblygonite-rich pegmatite deposits throughout the world. It was discovered in platy sheed form of 1mm hexagonal crystals. It was first described in 1977 by P.J. Dunn and D.E. Appleman from pegmatite collected from Bell Pit, Newry, Maine. Other specimens have been found in Kapunda, South Australia, in Silver Coin mine near Humboldt County, Nevada and various locations throughout Europe.

Composition The formula Ca3Al7(SiO4)3(PO4)4(OH)3·16.5(H2O) was determined by measuring its composition with x-ray spectroscopy giving the average amounts of SiO2 to be 13.72%, Al2O3 to be 27.17%, CaO to be 12.81%, P2O5 to be 21.61%, leaving 24.69% to be determined as H2O. The formula's essential elements are Al, Ca, H, O, P and Si with trace amounts of Sr. Common impurities of perhamite include Ti, Fe, Mg, Na, and F.

Physical properties Perhamite can range in color from white to brown and can be translucent to opaque. Its luster is said to be earthy, but vitreous to pearly along fractures. It occurs as radial discoidal, platy hexagonal crystals, in rough spherules up to 1mm thick. The specific gravity of perhamite is measured at 2.64 with a calculated density of 2.53. It is structurally related to minerals in the crandallite subgroup, namely Iangreyite.

Origin of the name Perhamite is named after Frank Croydon Perham (born 1934), an American geologist and pegmatite miner of West Paris, Maine who is currently part of the faculty of The Maine Pegmatite Workshop and has over 45 years experience in mining pegmatites. Frank Perham died on 31 January 2023.

Illustrations

Worked examples

Example 1 — a first encounter with Perhamite

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

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

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

Frequently asked questions

What is Perhamite in simple terms?

Perhamite is a phosphate mineral with the formula Ca3Al7(SiO4)3(PO4)4(OH)3·16.5(H2O). It occurs in rare isolated masses in amblygonite-rich pegmatite deposits throughout the world.

Why does Perhamite 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 Perhamite?

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 Perhamite.