Grade 7- Earth Science Review Section 3.1-3.3

Define stratum.

a horizontal rock layer that has a different type of rock layer above it

What lightweight, useful metal is extracted from the mineral bauxite?

aluminum

What is the most common igneous rock?

basalt

Why is coal called a fossil fuel?

because coal is used for fuel and is derived from the remains of once living things, it is called a fossil fuel

What is the hardest known naturally occurring substances?

diamonds

Define crystal.

geometric structures that are composed of atoms or molecules and have an orderly arrangement

Name two types of coarse-grained igneous rocks.

granite and gabbro

What term is defined as " a substance that is found naturally in the earth and has crystalline structure"?

minerals

What term describes any mineral containing a valuable metallic element?

ore

What two precious stones are forms of corundum?

ruby and sapphire

What is the most abundant sedimentary rock?

shale

What is the largest grout of minerals?

silicates

What alloy is made of iron and carbon?

steal

List seven characteristics that can be used to identify minerals.

surface color, streak color, luster, hardness, cleavage and fracture, specific gravity, and the axes

What is rock?

the hard material that makes up the earth's crust

Explain the difference between foliated and non-foliated metamorphic rocks.

Foliated metamorphic rocks are made up like leaves of a book. Non foliated metamorphic rocks are rocks that can not be split into thin layers like slate and other foliated rocks.

List and define the three main categories of rock that are based on the way rocks appear to have been formed.

Igenous rocks, which form from solidified magma; sedimentary rocks which are formed from sediment cemented together by water, pressure, and chemical action and metamorphic rocks which result when igneous or sedimentary rock are cooked by intense heat and pressure

what is the difference between intrusive and extrusive rock ?

Intrusive rock forms when magma cools and hardens while still underground, extrusive rock forms when magma reaches the surface and is extruded out of the earth as lava, the cool and hardened.

State the law of superposition.

It states that any undisturbed strata lie in the order they were laid down

Why are diamonds different in appearance compared to graphite if they are both made of carbon atoms?

the way diamonds were made gave them different crystal structures than graphite.

List the 4 Cs of a diamond.

weight, clarity, color and cut

what are the differences between mechanical, chemical, and organic sediments?

Mechanical sediments are sand, clay or rock fragments transported by physical means and deposited in a thick layer Chemical sediments form when mineral precipitate and separate out of solution Organic sediments are sediments made entirely of fossil material

Name two tests that are used to rate a mineral's hardness.

Mohs scale and the Brinell hardness test

What is the difference between precious and semiprecious stones?

Semiprecious stones are less race, durable and esteemed than precious stones

Explain the difference between synthetic and simulant gemstones

Simulant gemstones look like a natural gemstone but have different chemical and physical properties unlike; synthetic gemstones which look like their counterparts in appearance and chemical content.

Define specific gravity

Specific gravity is the ratio of the mass of any volume of a substance to the mass of an equal volume of water

What is a native element?

Substances that exist naturally in the earth's crust as single, uncombined elements

List nd define the three steps used in metallurgy.

1. extraction which the removal of ore from the earth. 2. refining which removes the impurities by heat, chemical action, or combination of the two, until a desired level of purity has been obtained. 3. shaping in which the purified ore into the desired object.

Could you accurately identify a yellow, vitreous mineral sample with a hexagonal shape? If not why ? What could you do to better identify the mineral?

The sample cannot be accurately identified because several minerals are yellow, vitreous and have a hexagonal shape. To identify the mineral, one could test the hardness, specific gravity and streak color.