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Index
 »Â
Gemmology
 »Â
Geology of Gems
 »Â
The Earth
level: The Earth
Questions and Answers List
level questions: The Earth
Question
Answer
What are the three separate compositions of planet Earth?
Core
What are the two types of crusts that make up the earths crust, that vary in density?
Continental
What is the earths crust made up of, which can move away, towards or past eachother, causing earthquakes, volcanoes and landscape formations which is where most gem material is formed?
Tectonic plates
What are the types of rocks that are formed from solidified magma, and also make up 95% of the earths crust?
Igneous
What is the name for volcanic rocks that are formed when magma breaks through the surface of the earth, and rapidly cools and crystallizes?
Extrusive igneous rocks
What is the name of the natural volcanic glass that is formed as magma cools rapidly at the earths surface?
Obsidian
What is the name for volcanic rocks that are formed when magma cools slowly beneath the earths surface?
Intrusive igneous rocks
What is the name of the intrusive igneous rocks that can contain large transparent crystals of gem material such as quartz, tourmaline, feldspar, beryl, zircon and topaz?
Pegmatites
What is present in magma that determines the type of minerals that are formed?
Chemical elements
What is the name of the solution of various chemicals that remains after magma has crystallized?
Hydrothermal
What happens when magma breaks through the upper layers of the earths crust and cools rapidly at the surface?
Crystallization