rocks

Question 1

types of rocks

Answer 1

Igneous
Sedimentary
Metamorphic

Question 2

rock cycle

Answer 2

All rocks on Earth are locked into a system of cycling and re-cycling.

Question 3

Sedimentary rocks

Answer 3

Rocks that are formed from erosion, deposition, and cementation.

Question 4

Igneous

Answer 4

rocks that are formed from melting and cooling

Question 5

Metamorphic

Answer 5

rocks that are formed by changing temperature and pressure

Question 6

Intrusive Igneous rocks

Answer 6

Slow cooling deep beneath the Earth’s surface allows crystals to grow to a large size (1/8” or more). These crystals are easily visible

Question 7

Extrusive Igneous rocks

Answer 7

Rapid cooling near or at the Earth’s surface produces many small crystals that are not readily seen by the unaided eye. Typically volcanic in origin, and Cooling may be so rapid that crystals do not have a chance to form and instead a glass is produced.

Question 8

Granite

Answer 8

a coarse to medium-grained rock that forms from the cooling of magma deep within the Earth (intrusive). It is made up mainly of varying amounts of the minerals: quartz, orthoclase, muscovite, biotite and hornblende. The name is from the Latin granum, for “grains”.

Question 9

PEGMATITES

Answer 9

classified as intrusive igneous rocks, but there is a difference. They are VERY coarse grained and strictly speaking are not crystallizing out of a magma.

Question 10

Diorite

Answer 10

very similar to granite, but is distinguished in the hand specimen by the absence of visible quartz.

Generally it has a salt and pepper appearance

Question 11

Gabbro

Answer 11

a coarse-grained rock that is high is iron & magnesium-bearing minerals (pyroxenes, amphiboles, plagioclase feldspar, olivene). The rocks will be dark in color, somewhat heavier than granitic rocks and devoid of quartz.

Question 12

Peridotite

Answer 12

or DUNITE is composed of 90-100% olivine. As a result it is characteristically olive-greens in color.

This material is thought to have originated in the upper mantle of the Earth.

Question 13

RHYOLITE

Answer 13

name comes from the Greek rhyo, from rhyax, “stream of lava”. It is formed when molten rock with the same composition as a high silica granite oozes to the Earth’s surface; and therefore cools quickly so only microscopic-

Question 14

ANDESITE

Answer 14

is the fine-grained equivalent of DIORITE. It tends to be a darker gray than rhyolite and is often porphyritic, with visible hornblende.

Question 15

BASALT

Answer 15

occurs as thin to massive lava. flows, sometimes accumulating to thicknesses of thousands of feet and covering thousands of square miles.

dark, fine-grained and often vesicular (having gas pockets). The pockets may be filled with secondary minerals

Question 16

Pahoehoe (basalt)

Answer 16

a feature that forms on the surface of very fluid basalt flows. Much like the skin on a bowl of tomato soup – the surface in contact with the air begins to crystallize, while the fluid lava below continues to flow. This drags the upper, still plastic, surface into a series of smooth wrinkles.

Question 17

OBSIDIAN

Answer 17

volcanic glass (an acrystalline “solid” –actually a supercooled liquid). Its glassy, lustrous and sometimes banded appearance makes it rather easy to distinguish from all other rocks.

Question 18

PERLITE

Answer 18

is a light gray volcanic glass, having numerous concentric cracks which give rise to a perlitic or onion skin structure. It is generally of rhyolitic composition. It also exhibits a pearly luster.

Question 19

PUMICE

Answer 19

highly vesicular (i.e. it has lots of gas bubble holes) and is of rhyolitic composition.
Due to the many small holes, it is lightweight and will often float in water.

Question 20

Tuff

Answer 20

the accumulation of ash and small pyroclastic debris. Thick beds may form for many miles around a very explosive volcano, such as Mt. St. Helens.
Often, when the material is still hot upon deposition, it welds into a very hard rock.

Question 21

Volcanic Breccia

Answer 21

is pyroclastic (fire-formed fragments) and forms in explosive eruptions.  It is a mix of large angular fragments and small ash.
Often, the material is hot when it comes to rest and cools (welds) into a very hard rock.

Question 22

CLASTIC

Answer 22

sedimentary rocks that are composed of particles of pre-existing rocks

Question 23

CHEMICAL/BIOCHEMICAL

Answer 23

sedimentary rocks are the result of either precipitation of solids from solutions (like salt from water) or by organic process, like shells from marine organisms.

Question 24

FOLIATED

Answer 24

Metamorphic rocks that exhibit parallel alignments of minerals

Question 25

NON-FOLIATED

Answer 25

Metamorphic rocks composed of minerals that are not elongated or flat, do not exhibit parallel alignments

Question 26

SHALE

Answer 26

the most common sedimentary rock