earth science

Simmonsite

Simmonsite 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 Simmonsite rather than just read about it. In short: Simmonsite is a halide mineral, being a tertiary light metal fluoride, with formula Na2LiAlF6. It was first discovered in nature in Mineral County in the Gillis Range of Nevada, U.S.A.

Key takeaways

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

Reference excerpt

Simmonsite is a halide mineral, being a tertiary light metal fluoride, with formula Na2LiAlF6. It was first discovered in nature in Mineral County in the Gillis Range of Nevada, U.S.A. The mineral is found intergrown with cryolite, cryolithionite and trace elpasolite. The mineral has a monoclinic structure of P2 or P2/m. The ideal chemical formula for simmonsite is Na2LiAlF6. The mineral has a no visible cleavage, Mohs hardness of 2.53, a pale white color with a white streak and feels somewhat greasy. Simmonsite was named for the Professor of Mineralogy and Petrology at the University of New Orleans, William B. Simmons.

Occurrence Simmonsite, cryolite and cryolithionite form together as part of the alumino-fluoride aassemblage in a late stage breccia pipe structure that cross the Zapot amazonite-topaz-zinnwaldite pegmatite located in the described location above in Nevada. This assemblage occurs with around a third of each of theses phases. The three phases form an intergrowth of anhedral to subhedral grains that can be micrometers to approximately two or three hundred micrometers in size. The main anhydrous alumino-fluorides results in size almost 20 cm or more across and weight more than 1 kg. Another assemblage of alumino-fluorides exist, some that contain water or hydroxyl, pachnolite, weberite, thomsenollite, prosopite, ralstonite, as well as a second generation of cryolithionite.

Physical properties Simmonsite contains no observable euhedral crystals but it does have complex polysynthetic twinning. Its color is pale buff to cream in the hadn specimens accompanied by a white streak and has a greasy appearance. It exhibits a hardness of 2.5-3 on the Mohs hardness scale. There is no apparent cleavage, a subconchoidal fracture, no parting, and is not brittle. The measured density is 3.05(2) g/cm3.

Optical properties The optical properties of this mineral were discovered by using the standard optical spindle stage procedure in 589 nm light. It was determined to have birefringence with a Berek compensator.

Chemical properties Simmonsite is a fairly simple mineral chemically as the only elements present in major or minor amounts are Na, Al, Li, and F. The empirical chemical formula for simmonsite is Na2LiAlF6. The four primary alumino-fluorides behave distinctly different under an electron beam with elpasolite and cryolithionite showing no beam damage with time, even though simmonsite did have some and cryolite having the greatest extent of damage.

Chemical composition

X-ray crystallography Natural simmonsite is monoclinic with P2 or P2/m. The unit cell dimensions are a=7.5006(6) Å, b= 7.474(1) Å, c= 7.503(1) Å, β = 90.847(9)°, V= 420.6(1) Å3, Z= 4. These dimensions are almost identical to those of babingtonite. Simmonsite has had a long history of it being difficult to understand as there have been previous studies trying to understand the crystallography. Errors were discovered in previous work by Holm and Holm(1970) that suggested it was monoclinic, B-centered, a=7.54 Å, b= 7.52 Å, c= 7.53 Å, β = 90.81°.

Worked examples

Example 1 — a first encounter with Simmonsite

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

In research: Simmonsite 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 Simmonsite 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: Simmonsite is common in secondary-school and first-year university syllabi. It links to neighbouring topics Minerals in space group 10, Minerals in space group 3, Monoclinic minerals, so understanding it makes those chapters shorter.
In everyday life: Look for Simmonsite 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 Simmonsite in 20 minutes

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

Frequently asked questions

What is Simmonsite in simple terms?

Simmonsite is a halide mineral, being a tertiary light metal fluoride, with formula Na2LiAlF6. It was first discovered in nature in Mineral County in the Gillis Range of Nevada, U.S.A.

Why does Simmonsite 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 Simmonsite?

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 Simmonsite.