Igneous Rocks

Question 1

Rocks that formed from the solidification of magma (intrusive) or lava which flowed out to the surface of the Earth.

Answer 1

Igneous Rocks

Question 2

Magma that reaches the Earth’s surface

Answer 2

Lava

Question 3

molten rock solidifies at the surface

-Aphanitic

Answer 3

Extrusive (Volcanic)

Question 4

• igneous rocks that form at depth

- Phaneritic

Answer 4

Intrusive (Plutonic)

Question 5

-rocks that formed from the consolidationof individual rock fragments ejected during a violent eruption.

Answer 5

Pyroclastic (Fragmental)

Question 6

Texture/Crystal Size
*- rapid cooling and high silica content of molten rock that is ejected into the atmosphere generates rocks having a glassy texture. This is formed from granitic or felsic magma.
* are rocks that consist of unordered ions
Ex. *

Answer 6

Texture/Crystal Size
Glassy Texture- rapid cooling and high silica content of molten rock that is ejected into the atmosphere generates rocks having a glassy texture. This is formed from granitic or felsic magma.
Glass are rocks that consists of unordered ions
Ex. Pumice and obsidian

Question 7

*Texture- produced from debris of explosive eruption.

Ex. Tuff, *, agglomerate, *

Answer 7

Pyroclastic

lapilli stone, volcanic breccia

Question 8

Pyroclastic Texture- produced from *

Ex. *, lapilli stone, *, volcanic breccia

Answer 8

debris of explosive eruption.

Tuff, agglomerate

Question 9

*- cooled quickly on or near Earth’s surface. These rocks are fine-grained and have size <2 mm. This texture can be observed from rocks formed from intermediate magma. Light-colored aphanitic rocks are those containing primarily nonferromagnesian silicate materials.
Ex. *

Answer 9

Aphanitic Texture

Rhyolite, Andesite, Basalt, and Komatiite

Question 10

Aphanitic Texture- cooled *on or near Earth’s *. These rocks are fine-grained and have size *. This texture can be observed from rocks formed from intermediate magma. Light-colored aphanitic rocks are those containing primarily nonferromagnesian silicate materials.
Ex. Rhyolite, Andesite, Basalt, and Komatiite

Answer 10

quickly, surface

<2 mm

Question 11

*- produced by slow then rapid cooling. The resulting rock has large crystals embedded in the matrix which are called *while the matrix of smaller crystals is called *. A rock with such a texture is termed *.

Answer 11

Porphyritic Texture
phenocrysts, groundmass
porphyry

Question 12

Porphyritic Texture- produced by *then *cooling. The resulting rock has * crystals embedded in the matrix which are called phenocrysts while the matrix of * crystals is called groundmass. A rock with such a texture is termed porphyry.

Answer 12

slow, rapid
large
smaller

Question 13

*Texture- coarse-grained texture produced when magma cools slowly at depth. Size: >2 mm.

Answer 13

Phaneritic

Question 14

*Texture – very large crystals with 3 cm in size

Answer 14

Pegmatitic

Question 15

Factors affecting the texture of Igneous Rocks

Answer 15

• Rate of magma cooling
• Amount of silica present
• Amount of dissolved gases

Question 16

Other classification of Igneous Rocks

*- contains tiny holes/vesicles which formed due to escaping gas bubbles in the lava or magma.

Answer 16

Vesicular

Question 17

• mineral precipitates, vesicles at the rock may be filled by low temperature minerals deposited in the cavities after the lava solidified

Answer 17

Amygdaloidal

Question 18

are an assemblage of mafic and ultramafic lavas and hypabyssal rocks found in association with sedimentary rocks like greywackes and cherts.

Answer 18

Ophiolites

Question 19

the initial process that occurs in the formation of a crystal from a solution, a liquid, or a vapour, in which a small number of ions, atoms, or molecules become arranged in a pattern characteristic of a crystalline solid, forming a site upon which additional particles are deposited as the crystal grows

Answer 19

Nucleation

Question 20

continues as more ions or molecules become attracted

Answer 20

Growth