What is the primary characteristic that defines a mineral as having a crystalline structure?

• It is found only in igneous rocks.

• It is always transparent.

• It has a repeating atomic pattern.

• It is made of organic materials.

Which of the following is a common feature of crystals?

• They have flat faces and polygonal cross-sections.

• They are only found in sedimentary rocks.

• They are always colorless.

• They are always spherical.

How are the atoms arranged in a cubic crystalline structure?

• In a repeating cube pattern.

• In a linear chain.

• In a random pattern.

• In a circular pattern.

Which mineral is known for having a hexagonal crystalline structure?

• Calcite

• Corundum

• Quartz

• Pyrite

What is the process called when crystals form from pre-existing rocks under heat and pressure?

• Sedimentation

• Evaporation

• Metamorphism

• Erosion

Which of the following is NOT a way crystals can form?

• Through biological processes

• By evaporation of water

• By rapid cooling of lava

• From solidified magma

What is a key difference between crystalline structures and natural glass?

• Natural glass has a repeating atomic pattern.

• Crystalline structures break along specific planes.

• Crystalline structures are always opaque.

• Natural glass is only found in volcanic regions.

What is obsidian, and how does it form?

• A type of rock formed by sedimentation.

• A type of glass formed by rapid cooling of lava.

• A type of mineral formed by slow cooling of magma.

• A type of crystal formed by biological processes.

Why is obsidian used in surgical tools?

• It is more durable than steel.

• It is ten times sharper than steel.

• It is more flexible than steel.

• It is more abundant than steel.

What happens to lava when it cools extremely quickly?

• It forms a crystalline structure.

• It forms large crystals.

• It forms sedimentary rock.

• It forms natural glass.