Igneous Rocks

How do geologists classify igneous rocks?

• By their color, weight, and size

• By their origin, texture, and mineral composition

• By their age, location, and hardness

• By their fossils, streak, and luster

What is extrusive rock?

• Igneous rock that hardens beneath Earth's surface

• Igneous rock formed from lava that erupted onto Earth's surface

• Sedimentary rock formed by the deposition of material at the Earth's surface

• Metamorphic rock formed by the alteration of existing rock by heat and pressure

What is intrusive rock?

• Igneous rock formed from lava that erupted onto Earth's surface

• Sedimentary rock formed by the deposition of material at the Earth's surface

• Igneous rock that has formed when magma hardens beneath the surface of Earth

• Metamorphic rock formed by the alteration of existing rock by heat and pressure

What does the texture of an igneous rock depend on?

• The color and weight of the rock

• The size and shape of its mineral crystals

• The age of the rock

• The location where the rock is found

What type of igneous rocks are formed by rapidly cooling lava?

• Coarse-grained rocks with large crystals

• Fine-grained rocks with small crystals or no crystals

• Intrusive rocks with large grains

• Extrusive rocks with a glassy texture

What characterizes slowly cooling magma in the formation of igneous rocks?

• It forms fine-grained rocks with small crystals

• It forms rocks with a glassy texture

• It forms coarse-grained rocks, such as granite, with large crystals

• It leads to the formation of intrusive rocks with small grains

Which of the following rocks is likely to be formed from lava that is high in silica?

• Basalt

• Granite

• Limestone

• Marble

Why is it sometimes important to look at the color of granite?

• To determine its age

• To determine its strength

• To determine its mineral composition

• To determine its weight

What was obsidian used for by Ancient Indigenous people?

• For building materials

• To make sharp tools for cutting and scraping

• For mixing with soils and starting vegetables

• For cleaning and polishing

What was the use of perlite according to notes?

• For making sharp tools

• For building materials

• For mixing with soils and starting vegetables

• For cleaning and polishing