earth science

Northstarite

Northstarite 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 Northstarite rather than just read about it. In short: Northstarite is an immensely rare lead-tellurite-thiosulfate mineral with an ideal formula of Pb6(Te4+ O3)5(S6+O3S2-). Northstarite was first discovered in 2019 by Charles Adan in the North Star Mine of the Tintic Mining District, Juab County, Utah, USA.

Key takeaways

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

Reference excerpt

Northstarite is an immensely rare lead-tellurite-thiosulfate mineral with an ideal formula of Pb6(Te4+ O3)5(S6+O3S2-). Northstarite was first discovered in 2019 by Charles Adan in the North Star Mine of the Tintic Mining District, Juab County, Utah, USA. Northstarite received its name after this type locality where it was originally discovered, the North Star Mine. Northstarite is the fourth thiosulfate mineral that exists on Earth, and although all thiosulfates have essential lead components, northstarite is the first thiosulfate species containing groups of both thiosulfate and tellurite (Te4+O3).

Occurrence Northstarite is a mineral found in the oxidation zone of Earth, meaning that it is found near the Earth's surface and formed as a result of the chemical decomposition of other minerals that are unstable at the surface. Northstarite occurs in small rock cavities with quartz, baryte, enargite, and pyrite, but is also associated with anglesite, azurite, chrysocolla, fluorapatite, plumbogummite, tellurite, zincospiroffite, and a type of copper-tellurite that possesses poor crystallization. Northstarite is associated with another new mineral called adanite, which was also discovered in the North Star Mine and shares a similar chemical composition as northstarite. The holotype specimen of northstarite originated from the holotype specimen of adanite.

Physical properties The crystals of northstarite are about 1 mm in length and are short and prismatic, with pyramidal terminations. The irregular or uneven faces of the crystals avert accurate measurements, but rough measurements have been recorded as {100}, {101}, and {101} based on the general appearance of the crystals and the Donnay-Harker Law. The crystals display no twinning or cleavage, and have an uneven fracture. Northstarite is very brittle. Based on scratch tests, the hardness of northstarite is approximately 2 on the Mohs scale of hardness. Northstarite displays an adamantine luster and has transparent to translucent crystals with a beige color and a white streak.

Optical properties Northstarite is a nonpleochroic and uniaxial negative mineral. The calculated average index of refraction for northstarite is 2.15 based on the empirical formula of Pb5.80Sb3+0.05Te4+5.04S6+1.02O18.

Chemical properties Northstarite is a thiosulfate mineral that contains tellurite. The empirical formula of northstarite is Pb5.80Sb3+0.05Te4+5.04S6+1.02O18. When simplified, this formula becomes an ideal formula of Pb6(Te4+ O3)5(S6+O3S2-). Chemically, northstarite resembles adanite, schieffelinite, and also eztlite to an extent. Northstarite is indicated to be an anhydrous mineral. When introduced to concentrated hydrochloric acid at room temperature, the crystals of northstarite are slowly soluble.

Chemical composition

* The measured SO3 in parentheses is allocated as SO3 and S based on S6+:S2– = 1:1

X-ray crystallography Northstarite is in the hexagonal crystal system with a space group of P63. The unit cell dimensions are a= 10.253 Å and c= 11.6747 Å with a standard unit cell volume of 1061.50 Å3. Powder diffraction data:

Worked examples

Example 1 — a first encounter with Northstarite

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

In research: Northstarite 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 Northstarite 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: Northstarite is common in secondary-school and first-year university syllabi. It links to neighbouring topics Hexagonal minerals, Lead minerals, Minerals described in 2020, so understanding it makes those chapters shorter.
In everyday life: Look for Northstarite 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 Northstarite in 20 minutes

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

Frequently asked questions

What is Northstarite in simple terms?

Why does Northstarite 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 Northstarite?

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 Northstarite.