earth science

Junitoite

Junitoite 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 Junitoite rather than just read about it. In short: Junitoite is a mineral with formula CaZn2Si2O7·H2O. It was discovered at the Christmas mine in Christmas, Arizona, and described in 1976.

Key takeaways

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

Reference excerpt

Junitoite is a mineral with formula CaZn2Si2O7·H2O. It was discovered at the Christmas mine in Christmas, Arizona, and described in 1976. The mineral is named for mineral chemist Jun Ito (1926–1978).

Description and occurrence Junitoite is transparent to translucent and is colorless, milk-white, or colored due to alteration. Crystals grow up to 5 millimetres (0.20 in) and have high quality faces. Junitoite occurs in fractures through pods of sphalerite. It formed by retrograde metamorphism and oxidation of tactite, also resulting in kinoite. The mineral is known from New Jersey and the type locality in Arizona. Junitoite occurs in association with apophyllite, calcite, kinoite, smectite, and xonotlite.

Crystal structure

In 1968, Jun Ito published the results of synthesis of various lead calcium zinc silicates. The formula of one phase, designated X3, was identified as probably CaZnSi2O6·H2O. When he described junitoite, Sidney Williams identified the mineral's formula as CaZn2Si2O7·H2O, based on communications with Ito. The mineral's crystal structure was first determined in 1985 and refined in 2012. The mineral crystallizes in the orthorhombic crystal system. The structure is formed by chains of corner-sharing ZnO4 tetrahedra linked together by Si2O7 tetrahedral pairs. Calcium ions occupy vacancies and coordinate to five oxygen atoms and one water molecule.

History The first known specimen of junitoite was collected from the Christmas mine at Christmas, Arizona, and entered the collection of Joe Ana Ruiz. Geologist Robert A. Jenkins noticed the mineral in kinoite specimens, submitting Ruiz's sample to Sidney A. Williams for study. Further samples came from the collections of Ruiz and Raymond Diaz. Williams identified the specimens as a new mineral and described it in the journal American Mineralogist in 1976. He named it junitoite in honor of Jun Ito, the mineral chemist who noted the compound of which the mineral is composed. The International Mineralogical Association approved the mineral as IMA 1975-042. The type material is housed in the University of Arizona, Harvard University, the National Museum of Natural History, the University of Paris, the National School of Mines, and The Natural History Museum.

References

Bibliography Hamilton, R. D.; Finney, J. J. (March 1985). "The structure of junitoite, CaZn2Si2O7·H2O" (PDF). Mineralogical Magazine. 49 (350): 91–95. Bibcode:1985MinM...49...91H. doi:10.1180/minmag.1985.049.350.13. S2CID 140636176. Williams, Sidney A. (November–December 1976). "Junitoite, a new hydrated calcium zinc silicate from Christmas, Arizona" (PDF). American Mineralogist. 61 (11–12): 1255–1258. Yang, Hexiong; Jenkins, Neil G.; Downs, Robert T. (2012). "Redetermination of junitoite, CaZn2Si2O7·H2O" (PDF). Acta Crystallographica Section E. E68 (10): i73. doi:10.1107/S1600536812037622. PMC 3470120. PMID 23125564.

External links

Images of junitoite from mindat.org

Illustrations

Worked examples

Example 1 — a first encounter with Junitoite

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

In research: Junitoite 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 Junitoite 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: Junitoite is common in secondary-school and first-year university syllabi. It links to neighbouring topics Calcium minerals, Hydrates, Minerals described in 1976, so understanding it makes those chapters shorter.
In everyday life: Look for Junitoite 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 Junitoite in 20 minutes

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

Frequently asked questions

What is Junitoite in simple terms?

Junitoite is a mineral with formula CaZn2Si2O7·H2O. It was discovered at the Christmas mine in Christmas, Arizona, and described in 1976.

Why does Junitoite 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 Junitoite?

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 Junitoite.