Quiz on minerals and rocks featuring questions about hardness, break patterns, rock formation, and identifying extrusive igneous rocks.

Let’s go through each question one by one, step by step.

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Question 1:
> If a mineral scratches a fingernail, but is scratched by the copper penny, how hard is it?

We use the Mohs Hardness Scale to measure how hard minerals are. Here’s what we know:

- Fingernail = about 2.5 on the scale
- Copper penny = about 3.5 on the scale

If the mineral can scratch a fingernail (harder than 2.5), but gets scratched by a penny (softer than 3.5), then its hardness must be between 2.5 and 3.5.

Looking at the options:
- A) 4 → too hard (would scratch penny)
- B) 3 → fits! Between 2.5 and 3.5
- C) 3.5 → same as penny — wouldn’t get scratched by it
- D) 2.5 → same as fingernail — wouldn’t scratch it

✔ So the correct answer is B) 3

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Question 2:
> The minerals pictured break in which pattern?

The picture shows three different mineral samples with smooth, flat surfaces where they broke. That’s called cleavage — when a mineral breaks along flat planes because of its internal structure.

“Fracture” means breaking unevenly or jaggedly (like glass). “Both” or “Neither” don’t fit here since all shown pieces have clean breaks.

✔ So the correct answer is B) Cleavage

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Question 3:
> All of the following are necessary for a sedimentary rock to form, EXCEPT:

Sedimentary rocks form from layers of sediments that get pressed together over time. The key steps are:

- Weathering & Erosion → breaks down rocks into small pieces (sediments)
- Sediments → those tiny pieces pile up
- Pressure → squishes them together into rock

Heat is NOT needed for most sedimentary rocks — heat is more for metamorphic or igneous rocks.

So the thing that’s NOT necessary is Heat.

✔ Correct answer: B) Heat

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Question 4:
> Which of the pictured rocks is an EXTRUSIVE igneous rock?

Extrusive igneous rocks form when lava cools quickly on Earth’s surface. They usually look dark, glassy, or fine-grained.

In the image:
- Left rock looks lighter, maybe coarse — could be intrusive (cooled slowly underground)
- Right rock is black and shiny/glassy — classic sign of extrusive rock like obsidian

✔ So the correct answer is B) Right

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Final Answer:
1. B
2. B
3. B
4. B