Earth Science Igneous Rock Classifications

Question 1

-Composed of very large crystals (larger than 2-3 cm)

Answer 1

Pegmatitic

Question 2

-Mineral crystals that are visible without the aid of a magnifying lens.

Answer 2

Phaneritic

Question 3

-Texture that contains large crystals in a fine grained matrix.

Answer 3

Porphyritic

Question 4

-Visible crystals with the help of a magnifying lens.

Answer 4

Aphanitic

Question 5

-Result of gases escaping (holes in the structure)

Answer 5

Vesicular

Question 6

-Glass in texture in its structure.

Answer 6

Glassy

Question 7

-Pyro (fire) and klastos (shattered), distinguished from the size of its particle components

Answer 7

Pyroclastic

Question 8

What are the 3 crystal sizes

Answer 8

1. Glassy
2. Fine
3. Medium
4. Coarse

Question 9

-Light-colored (white, light gray, tan and pink)
-Rich in aluminum and silica.

Answer 9

Felsic

Question 10

-Dark-colored (black and brown)
-Rich in iron and magnesium.

Answer 10

Mafic

Question 11

-Rocks that form from slowly cooled magma that have time to form large visible mineral crystals.
-Can take thousands of years
-Happens inside

Answer 11

Intrusive/Plutonic

Question 12

-Rocks that form from rapidly cooled magma.
-Can take seconds to months
-Happens outside

Answer 12

Extrusive/Volcanic