Science Science ROCKS!!!ROCKS!!!

ROCKS AND MINERALS!

Earth’s ResourcesFocus Question:What properties make an Earth resource important?

• Earth resources have properties that make them important and useful.•Properties that determine the usefulness of an ore or mineral may be identified using a chart, diagram or dichotomous key.

Minerals!• Natural, solid materials found on Earth that are

the building blocks of rock; each has a certain chemical makeup and set of properties that determine their use and value.

Minerals continued…• Mineral are homogeneous, meaning the

same all the way through• Minerals can be called a “Earth material”• These naturally occurring homogeneous

substances (such as stone, coal, salt, sulfur, sand, tin, iron and zinc) are usually obtained from the ground.

• There are about 3000 known minerals on Earth

Minerals are not made by people; they are …

…naturally occurring substances. But since they were never living we call them inorganic.

Examples of MineralsQuartz Calcite

Iron

Hematite Diamond

Uses of MineralsQuartz makes

glass.Diamonds make

jewelry.

Many things that we see and use every day are made from iron.

Physical Properties• Density• Luster• Color• Streak • Texture• Hardness (Moh’s Scale)

Density (or Specific Gravity) is a very important property of minerals. The calculation is fairly simple - weight/volume.

Which property means the way the light bounces off the mineral?

What words can be used to describe a mineral’s luster?

•Metallic (shiny like a metal)•Shiny (like a diamond)•Glassy•Resinous (looks like sap, gum, pitch, or tar)•Pearly•Oily or greasy•Silky (appears to have fibers like a woven fabric)

Why is color not the best property to use to identify a mineral?

Many minerals have the same color.

slate limestone

StreakStreak• Streak color: Use the

back of a bathroom tile as a streak plate. Rub the mineral across it and examine the color of the streak.

Hardness: What are three testers that can be used to determine a mineral’s hardness?

fingernail, penny, nail

Moh’s Hardness Scale• This scale is relative. You assign a number to a mineral by

seeing what scratches what. To get the range of hardness for a sample do this: Try scratching it with your fingernail. If you can, the Moh’s scale hardness value is 2.5 or less.

• Try scratching with a penny. If you can, the value is 3.5 or less.

• Try scratching with a steel nail. If you can, the value is 5.5 or less.

• See whether the mineral will scratch glass. If it will, the Moh’s value is 6 or more.

Your fingernail has a hardness of 2.5 on the Mohs scale. If you can scratch a mineral with your fingernail, it must be softer than 2.5. If you can't scratch it, it must be harder than 2.5.

A pocket knife has a hardness of 5.5 on the Mohs scale. If your knife can scratch a mineral, it must be softer than 5.5. If it can't, then it must be harder than 5.5.

Moh’s Hardness Scale

Dichotomous Key• A dichotomous key is a tool that allows the

user to determine the identity of items in the natural world, such rocks, and minerals, based upon their properties.

• The keys consist of a series of choices that lead the user to the correct name of a given item.

• "Dichotomous" means "divided into two parts". Therefore, dichotomous keys always give two choices in each step.

Time to practice identifying minerals!

Minerals and Rocks- What is the

difference?Rocks are made of one or more

minerals

All rocks are made of 1 or more mineral, but minerals are not made of rocks.

What are rocks?

Rocks are made of minerals. Some rocks are made of just one, while others are made of many.

Rock Words: There are many common names for rocks and the usually give you an idea of how big the rock is. Here are a few:

mountain - huge, giant hunk of rock that is still attached to the earth's crust, doesn't move, tallboulder - large, taller than a personrock - large, you could get your arms around it or a bit smaller but it is usually jagged, broken off a bigger piece of rockriver rock - round rocks that are along the edge & at the bottom of fast-flowing riversstone - medium, you could hold it in two handspebble - small, you can hold it with two fingers, could get stuck in your shoe, usually roundedsand - made up of tiny pieces of rock, grains of sandgrain - tiny, like a grain of rice or smaller, often found on a beachdust - really fine powder that is mixed in with sand or soilspeck - as in a speck of dirt

How Rocks Form

Flowing water, exploding volcanoes, and heat and pressure from inside the Earth all form the three types of rocks.

Uses of Rocks• Building

• Machines & Tools • Consumables & Processes

• Decorations• Jewelry• Statues

• Electricity and heat

The Three Types of Rocks

Igneous Rock Sedimentary Rock

Metamorphic Rock

Igneous RockIgneous Rocks are formed from the cooling of magma which comes from volcanoes.  Some magma cools below the surface of the earth to form hard rocks like granite.  Some magna cools above the earth to form light rocks like basalt.

Igneous rocks are called fire rocks and are formed either underground or above ground.

Underground, they are formed when the melted rock, called magma, deep within the earth becomes trapped in small pockets. As these pockets of magma cool slowly underground, the magma becomes igneous rocks.

Igneous rocks are also formed when volcanoes erupt, causing the magma to rise above the earth's surface. When magma appears above the earth, it is called lava. Igneous rocks are formed as the lava cools above ground.

Melted rock below the Earth’s surface is called…

Melted rock above the Earth’s surface is called…

The breaking down and wearing away of rocks is called…

Small bits and pieces of rocks are called…

The movement of sediments from one place to another is called…

Sedimentary Rocks are formed on the earth's surface.  Sedimentary rocks are made from broken rocks and minerals.  They can, also, be made from hardened plants and animals.

DepositionDeposition is the settling of sand and sediment.  (ex. settles to bottom of sea)

Sedimentary RocksSedimentary rocks are formed in three steps:•Layers of sediment are deposited at the bottom of seas and lakes.•Over millions of years the layers get squashed by the layers above.•The salts that are present in the layers of sediment start to crystallize out as the water is squeezed out. These salts help to cement the particles together.

Compaction:happens when sediments are deeply buried, placing them under pressure because of the weight of overlying layers. This squashes the grains together more tightly. 

Cementation:is where new minerals stick the grains together – just as cement (from a bag) binds sand grains in a bricklayer’s mortar. If you look carefully at the microscope photo, you can see mineral crystals that have grown around the sediment grains and bonded them together. 

http://www.geolsoc.org.uk/gsl/pid/3559;jsessionid=27FA20936B5A38F77EB3F2707466002B

Metamorphic Rocks are rocks which have been changed by temperature and/or pressure.  Metamorphic rocks are "morphed" or changed below the earth's surface.  Sedimentary and igneous rocks can become metamorphic rocks.

What is any trace, mark, or remains of an organism called?

How old must a fossil be?

10,000 years

Now that’s old!!

What kind of rock are fossils usually preserved in?

Why do scientists study fossils?

They study them to learn about extinct plants and animals.

The Rock Cycle

The Earth is active. As you are reading this:•Volcanoes are erupting and earthquakes are shaking;•Mountains are being pushed up and are being worn down;•Rivers are carrying sand and mud to the sea;•Huge slabs of the Earth's surface called tectonic plates are slowly moving - about as fast as your fingernails grow.

http://www.learner.org/interactives/rockcycle/diagram.html

OK, so maybe it get a little

more complicated…