earth science

Hexahydroborite

Hexahydroborite 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 Hexahydroborite rather than just read about it. In short: Hexahydroborite is a mineral composed of calcium, boron, oxygen, and hydrogen, with formula CaB2H12O6, more precisely [Ca2+]([B(OH4)]−)2·2H2O. Hexahydroborite is the end member of a series of natural metaborates with the general formula CaB2O4·nH2O or CaO·B2O3·nH2O with n varying from 0 to 6, the other end member being anhydrous calciborite CaB2O4.

Key takeaways

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

Reference excerpt

Hexahydroborite is a mineral composed of calcium, boron, oxygen, and hydrogen, with formula CaB2H12O6, more precisely [Ca2+]([B(OH4)]−)2·2H2O. Hexahydroborite is the end member of a series of natural metaborates with the general formula CaB2O4·nH2O or CaO·B2O3·nH2O with n varying from 0 to 6, the other end member being anhydrous calciborite CaB2O4. The anion in the structure is tetrahydroxyborate, [B(OH4)]−. The name comes from an interpretation of the formula as CaBO3·6H2O.

History and occurrence The mineral was originally described by M. A. Simonov in 1976 from a sample found in a kurchatovite-sakhaite ore deposit in Solongo, Buryat Republic. The sample was recovered from 200 m underground, associated with pentahydroborite. the hexahydroborite was identified by X-ray diffraction. Gas/liquid inclusions suggest that the hexahydroborite crystallized after the pentahydroborite. The mineral was identified also at a location in Fuka, Japan. It occurred in a layer between crystalline limestone and skarns, in association with olshanskyite and calcite. It was conjectured to be formed by hydrothermal alteration of takaedite at low temperatures, around 250 °C. The mineral was synthesized in 2011.

Structure The structure (observed in the synthetic material) consists of infinite columns parallel to the c axis, identically oriented, displaced along the other two axes and linked only by hydrogen bonds. The columns are formed by calcium polyhedra linked together and to B(OH)4 orthotetrahedra by sharing edges. The crystal cell is monoclinic with the following parameters:

The density calculated for the synthetic version is 1.891 g/cm3.

Properties The mineral occurs in nature as flattened prismatic crystals, clear and transparent, with density 1.84 to 1.87 g/cm3 and Mohs hardness 2.5. The crystals may exhibit bluish-white photoluminescence. The mineral is optically biaxial positive with 2V = 83°. The refractive index is 1.50, with slightly increasing values for α, β, and γ; the difference γ−α is 0.012 by Simonov, and 0.007 by Kusachi. It has strong dispersion, increasing from violet to red. The compound is slowly soluble in water and insoluble in ethanol, contradicting an earlier report. It is promptly dissolved by hydrochloric, sulfuric, and acetic acid. On heating, it loses a significant amount of water between 90 and 110 °C, but dehydration is complete only over 800 °C, leaving anhydrous calcium metaborate CaB2O4. The synthetic version was obtained by recrystallization of calciborite CaB2O4 from H2O in presence of B2O3 at 250 °C and 70–80 atm.

References

Worked examples

Example 1 — a first encounter with Hexahydroborite

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

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

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

Frequently asked questions

What is Hexahydroborite in simple terms?

Why does Hexahydroborite 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 Hexahydroborite?

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 Hexahydroborite.