MCAS Science ReviewEarth and Space Science

Rocks and Their PropertiesOverview

1. What is a mineral? 2. What are the names of some minerals? 3. How are minerals different from rocks?4. What are some of the physical properties of

minerals that can be tested? 5. Describe how the three main categories of rocks

(metamorphic, sedimentary, and igneous) are formed.

6. Describe the rock cycle.

What is a mineral?

Minerals are the building blocks of rocks. Rocks are made of combinations of minerals.

Minerals are inorganic; they are not alive and they are not plants or animals. An example of a rock that is not a mineral is coal. Coal is a substance formed from decayed plants and animals. Therefore, coal is not considered a mineral.

Minerals are found in the earth or are naturally occurring substances. They are found in dirt, rocks, and water. They are not made by humans.

Minerals are chemical substances. Some minerals like gold or silver are made of only one element. Other minerals, like quartz and calcite, are combinations of two or more elements.

Minerals always have the same chemical makeup. For example, quartz will always consist of one part silicon (an element) two parts oxygen (another element).

What are the names of some minerals and rocks?

Minerals are usually solid crystals. They have a number of flat surfaces in an orderly arrangement. For example, a crystal of quartz is always hexagonal because of the way the atoms of silicon and oxygen join together.

About 2,000 minerals have been found. Oxygen is part of many minerals. Minerals containing oxygen make up almost half of the earth's crust. Quartz is a common mineral. Other common minerals are feldspar, mica, and horneblend. Many rocks are made of these common minerals.

Some minerals are rare and expensive. They are called gems . Diamonds, rubies, and emeralds are good examples of such minerals. Gold and silver are also minerals. Together, these natural substances are used to make beautiful jewelry.

Mineral Versus Rocks

How are minerals different from rocks?

Minerals have a single molecular or atomic structure throughout. Many are crystals, like quartz or diamond. Others are metallic like silver and gold. All are inorganic, or non-living.

Rocks are made up of different minerals. Their chemical composition depends on the minerals and other materials in them. Rocks may include both inorganic and organic material.

Mineral TestsWhat are some of the physical properties of

minerals that can be tested?

hardness -- Hardness is a measure of a mineral's resistance to abrasion (scratching) and reflects the atomic structure of a mineral. It is measured using the Mohs Hardness Scale. The mineral is scratched with various objects, then rated on the Mohs Hardness Scale.

color – The color of a mineral is tested with the eyes.

luster – How a mineral reflects light is its luster. Look at the mineral and use some of the following terms to describe its luster: metallic, pearly, greasy, waxy, dull.

cleavage (shape) -- Cleavage describes how a crystal breaks when subject to stress on a particular plane or surface. If part of a crystal breaks due to stress and the broken piece retains a smooth plane or crystal shape, the mineral has cleavage. A mineral that never produces any crystalline fragments when broken off has no cleavage.

•           Finger Nail (H = 2.5)

•           Knife Blade (H = 5.5)

• Penny (H = 3)

Mineral TestsWhat are some of the physical

properties of minerals that can be tested?

streak – Streak is the color of the mineral when it is powdered. Using a white and a black streak plate, the mineral is stroked across the plate and the color observed with the eyes.

magnetism – Magnetism is whether or not the mineral attracts a magnet.

transparency -- The amount of light able to be passed through a mineral determines its transparency . Light is able to pass through transparent minerals; translucent minerals partially let light pass through; and opaque minerals do not let any light through.

smell – The odor or smell of the rock.

What are the three categories of rocks?

How are they formed?

Igneous rocks are formed from cooled magma underground or lava from volcanoes above ground. In the top picture, lava flowing from a volcano in Hawaii forms igneous rocks.

Sedimentary rocks are formed underwater when sediments like mud, sand, shells, and pebbles on the ocean floor are pressed until they become rock. In the middle picture, sedimentary and metamorphic rocks in Arizona were broken into sediments and carried away, leaving the Grand Canyon behind.

Metamorphic rocks are formed when heat and pressure transform igneous or sedimentary rocks. In the bottom picture, metamorphic rocks in Arizona show formerly flat sedimentary layers squeezed into new shapes.

Rock Cycle

Soil How is soil formed?

There are four basic “ingredients” that go into the “recipe” for making soil: tiny pieces of rock (called inorganic material), decayed plants and animals (called organic material), water, and air.

When small pieces of rock break off larger ones, they form the basis of all soil. This breaking can occur through weathering and erosion:

weathering – rocks are broken into smaller pieces in two ways:

1.chemical weathering – when water dissolves or rusts away rocks2.physical weathering – when wind, water, ice, temperature changes, glaciers, animals, and plants break off pieces of rock

erosion – when smaller pieces of rock are moved away by water, wind, ice, glaciers, rocks, etc.

Soil

Because soils develop under a variety of conditions, the soil in one location can be very different from the soil in another location. In order to understand soil and how one soil differs from another, geologists look at and measure the soil’s properties.

color – determined by the organic or inorganic materials

texture – the size of particles in the soil

water retention ability – determined by texture of particles

water and air content – determined by location of soil, as well as its texture and composition

Weather

1. Describe the four main weather factors. (Remember our acronym, WHAM: wind, heat, air pressure, and moisture.)

2. How do the main weather factors combine with geography to create the weather in a particular place and season?

3. How do the revolution of the earth around the sun, the earth’s rotation, and its tilt cause our seasons?

4. What are the various forms of precipitation?5. What determines the type of precipitation that

occurs? 6. How do global patterns such as the jet stream and

water currents influence local weather in measurable terms, such as temperature, wind direction and speed, and precipitation?

7. How are weather and climate the same and different?

Main Weather Factors

Remember our acronym, WHAM: wind, heat, air pressure, and moisture.wind – the movement of air in a horizontal direction; local winds (sea, land, and mountain breezes) are caused by local geography, while global wind patterns (westerlies, easterlies, jet stream) are caused by global rotation

heat – the sun’s energy travels to the earth as radiant energy, which is light and heat, but this energy only raises temperature when it encounters material

air pressure – the weight of air in a certain space or altitude, caused by gravity holding the atmosphere down on the Earth

moisture – water in the atmosphere

Weather and GeographyHow do the main weather factors combine with geography to

create the weather in a particular place and season?

Local geography, like oceans, large lakes, and mountains can affect weather in an area. Prevailing winds and presence or absence of the jet stream will also affect weather. In MA, the Berkshire Hills in the west and the ocean in the east, westerly prevailing winds, ocean winds, and the jet stream all affect local weather.

The SeasonsHow do the revolution of the earth around the sun, the earth’s

rotation, and its tilt cause our seasons?

The 23o tilt of the Earth as it revolves annually around the sun determines the seasons. When a hemisphere is leaning toward the Sun, there are higher temperatures and longer periods of daylight.

Forms of Precipitation

What are the various forms of precipitation?

Snow, rain, hail, and sleet are all forms of precipitation.

Forms of PrecipitationWhat

determines the type of

precipitation that occurs?

Temperature in the clouds, in the air through which it falls, and on the surface determines the form of precipitation.

Forms of Precipitation -- Hail

How does hail form?

Hail forms in cumulonimbus clouds when electrical charge become unequal, temperatures vary from below to above freezing, and water droplets move up and down in air currents in these huge, tall clouds.

Global Weather PatternsHow do global patterns such as the jet stream and

water currents influence local weather in measurable terms, such as temperature, wind direction and speed, and precipitation?

The jet stream brings cooler air to the USA, while the Gulf Stream warms the waters of Atlantic Ocean. Other parts of the world have different ocean currents, jet stream, and other global wind patterns.

Weather and ClimateHow are weather and climate the same and different?

The climate of a region is its weather over many months and years. Climates can be described using terms like polar, temperate, and tropical. Massachusetts is in a temperate climate zone.

The Water Cycle • Describe the four parts of the water cycle? (Remember our

acronym CAPE: condensation, accumulation, precipitation, and evaporation (terms not in order).)

• How does the water cycle affect the climate of a place?