earth science

Greenwoodite

Greenwoodite 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 Greenwoodite rather than just read about it. In short: Greenwoodite is the second mineral discovered in the Wigwam deposit of southeastern British Columbia, Canada. It is compositionally and structurally distinct, but compositionally related to zoltaiite, the first new mineral described from this locality.

Key takeaways

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

Reference excerpt

Greenwoodite is the second mineral discovered in the Wigwam deposit of southeastern British Columbia, Canada. It is compositionally and structurally distinct, but compositionally related to zoltaiite, the first new mineral described from this locality. The name is in honor of Hugh J. Greenwood, retired professor and former head of the Geological Sciences Department at the University of British Columbia, Vancouver, British Columbia, Canada. Grain size, polyhedral grain boundaries, and the general lack of secondary mineralization indicate that greenwoodite is part of a prograde metamorphic assemblage. The ideal chemical formula for greenwoodite is Ba2-x(V3+OH)xV9(Fe3+, Fe2+)2Si2O22.

Occurrence Greenwoodite is part of the prograde assemblage in a greenschist facies metamorphosed Mississippi-Valley type base-metal deposit. Greenwoodite is found as part of a suite of three minerals: greenwoodite, zoltaiite, and batisivite. All three minerals are found together in the Wigwam Deposit of British Columbia. All three of these minerals occur as trace phases within an assemblage of quartz, celsian, apatite, sphalerite, pyrrhotite, galena, and pyrite. Greenwoodite occurs as small, disseminated semi-prismatic to tabular grains. Irregular grains intergrown with other phases are common as well. Grains of greenwoodite can range from areas of 800 microns to 20,000 microns. The grains of greenwoodite can be found isolated, but are generally found in groups of 2-10 closely-spaced groups.

Properties

Physical Greenwoodite is a black and/or opaque mineral that has a sub-metallic/dull luster. On the Mohs Scale of Mineral Hardness, greenwoodite is a 5. Greenwoodite has one perfect plane of cleavage which is found on the {001} plane. The tenacity of Greenwoodite is brittle meaning it breaks or shatters very easily. The calculated density of greenwoodite is 4.81 g/cm3.`

Optical In reflected light, greenwoodite has a low reflectance (similar to that of sphalerite), gray color with a weak brownish tint, no internal reflections, and distinct bireflectance, pleochroism, and anisotropy with straight extinction relative to its cleavage direction.

Chemical The empirical formula for greenwoodite is Ba0.60(V3+OH)0.40(V3+8.33, Cr0.33, Ti0.13, Al0.13, Mn3+0.02)Σ9(Fe3+1.08, Fe2+0.60, Zn0.22, Al0.06, Mg0.04)Σ2(Si1.72, Fe3+0.28)Σ2O22

Composition

Structure Greenwoodite is part of the Trigonal System with a Space Group of P3m1. The unit cell dimensions are a = 5.750 Å, b = 5.750 Å c = 14.459 Å; α=90.00° β=90.00°, γ=120.00°. The calculated X-Ray Powder pattern is 2.925 (100), 2.875 (38), 2.469 (35), 1.438 (35), 2.354 (28), 2.212 (28), 1.669 (26).

Worked examples

Example 1 — a first encounter with Greenwoodite

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

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

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

Frequently asked questions

What is Greenwoodite in simple terms?

Why does Greenwoodite 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 Greenwoodite?

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 Greenwoodite.