earth science

Impactite

Impactite 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 Impactite rather than just read about it. In short: Impactite is rock created or modified by one or more impacts of a meteorite. Impactites are considered metamorphic rock, because their source materials were modified by the heat and pressure of the impact.

Key takeaways

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

Reference excerpt

Impactite is rock created or modified by one or more impacts of a meteorite. Impactites are considered metamorphic rock, because their source materials were modified by the heat and pressure of the impact. On Earth, impactites consist primarily of modified terrestrial material, sometimes with pieces of the original meteorite.

Formation When a large meteorite hits a planet, it can radically deform the rocks and regolith that it hits. The heat, pressure, and shock of the impact changes these materials into impactite. Only very massive impacts generate the heat and pressure needed to transform a rock, so impactites are created rarely.

Characteristics Impactite includes shock-metamorphosed target rocks, melts (suevites) and mixtures of the two, as well as sedimentary rocks with significant impact-derived components (shocked mineral grains, tektites, anomalous geochemical signatures, etc.). In June 2015, NASA reported that impact glass has been detected on the planet Mars. Such material may contain preserved signs of ancient life—if life existed. Impactites are generally classified into three groups: shocked rocks, impact melt, and impact breccias.

Shocked rock Shocked rocks have been transformed by shock metamorphism caused by the impact. They include shatter cones and high-pressure minerals, for example coesite and stishovite.

Impact melts When a meteor strikes a planet's surface, the energy released from the impact can melt rock and regolith into a liquid. When the liquid cools it forms a solid known as an impact melt. If the liquid solidifies quickly before the atoms arrange into a crystal lattice, it forms an impact glass. Impact glass can be dark brown, almost black, and partly transparent. Sometimes, the cooled liquid does form a crystal structure. In that case, it would still be considered an impact melt, but not an impact glass.

Tektites

Tektites are a rare kind of impact glass.

Impact breccias

Breccia is "a rock consisting of angular fragments cemented together". An impact breccia is formed when a meteor shatters a rock and then cements it back together. Some breccias contain impact melts.

Examples of impactite

Impactite has been found, for example, at the following impact craters and structures:

Alamo bolide impact (Late Devonian), Nevada, United States Alga crater on the planet Mars Barringer crater, Arizona, United States Charlevoix impact structure, Québec, Canada Darwin Crater, Tasmania (source of Darwin glass) Lake Lappajärvi, Finland (source of Kärnäite) Manicouagan impact structure, Québec, Canada Neugrund crater, Estonia Nördlinger Ries crater, Germany Rochechouart impact structure, France Stac Fada Member, Scotland Wabar craters, Saudi Arabia

See also Glossary of meteoritics Meteorite shock stage – Measure of the degree of fracturing of the matrix of a common chondrite meteorite Vitrified sand

References

External links

Meteorite crater glossary

Illustrations

Worked examples

Example 1 — a first encounter with Impactite

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

In research: Impactite 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 Impactite 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: Impactite is common in secondary-school and first-year university syllabi. It links to neighbouring topics Glass in nature, Impact event minerals, Metamorphic rocks, so understanding it makes those chapters shorter.
In everyday life: Look for Impactite 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 Impactite in 20 minutes

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

Frequently asked questions

What is Impactite in simple terms?

Why does Impactite 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 Impactite?

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 Impactite.