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Science Experiments – Are Rocks Really Solid?

Looking for a great science experiment? How about an Earth Science project? Have you heard the expression “as solid as a rock”. Hold up just a minute there; rocks are not quite as solid as most of us believe. Rocks have little pockets of air inside them. Have you ever looked at a piece of volcanic rock? The air pockets are really easy to see. But even in very dense rocks like granite for example, there are tiny pockets of air inside. This is a great subject for an interesting science experiment!

One way to tell the difference in rocks is to pick up two rocks of about the same size. One rock is volcanic and the other rock is granite. You will quickly discern that the granite rock is heavier. This is because it is denser, has smaller air pockets and therefore weighs more than the volcanic rock which is less dense and has bigger air pockets.

You can do an experiment where you will investigate the difference in rocks to see which are more porous, leaving more room for air and gas, and weighing less.

Of what practical interest is a science fair project on the earth science of rocks? The porosity of rock is important to all industries that use rock. In road building, in oil and gas exploration and in many other industries, the porosity of rock is a factor that looms large.

There are many factors that influence rock porosity. In this science experiment you will investigate the effect of particle size on porosity by making a model to test your hypothesis. You will attempt to determine which particles leave the most space and make a more porous matrix, small particles or large particles.

You will attempt to determine how porosity is related to particle size, how much space is left between particles of rock or soil, and how porosity can be measured.

For this experiment you will need clear plastic cups, water, a permanent marker, a measuring cup, and different size rock particles. You want about seven or eight different rock samples. You can get them from your garden, or from a landscape or construction supply company. Get different sizes. Fill each plastic cup with your samples and label the cups with the size of the particles.

Fill your measuring cup with water to the 100 milliliter mark. Pour water into the first sample until full. Make careful records of the amount of water left in the measuring cup. Record your results in a table. Determine the amount of empty space in the sample.

You should subtract the amount of water you measured from 100 ml. If after pouring water into the sample cup, there was 60 ml of water left, you would subtract 60 ml from 100 ml. You will have determined that there is a volume of 40 ml of space between the particles in your cup.

Repeat the above procedures for each sample. Make a chart to compare your results. Which sample had the most empty space. Which sample had the least.

Do you see a relationship between particle size and pore space? You can vary this experiment by using other materials like volcanic rock, or limestone or sandstone or quartz. You may also wish to try using different soils like clay, loam or sandy soil.

In case you are wondering why there are so many different kinds of rocks you may be interested in knowing that all rocks are formed and categorized as being igneous, sedimentary and metamorphic.

For thousands, even millions of years, little pieces of our earth have been eroded–broken down and worn away by wind and water. These little bits of our earth are washed downstream where they settle to the bottom of the rivers, lakes, and oceans. Layer after layer of eroded earth is deposited on top of each.

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.

Sedimentary rocks are formed in two ways. Some are formed by pressing together or compacting loose particles which have been deposited on land or in water bodies such as seas or lakes. These loose particles are called sediments. Other sedimentary rocks are formed by the crystallization of dissolved minerals.

Metamorphic rocks are rocks that have “morphed” into another kind of rock. These rocks were once igneous or sedimentary rocks. The rocks are under tons and tons of pressure, which fosters heat build up, and this causes them to change. If you exam metamorphic rock samples closely, you’ll discover how flattened some of the grains in the rock. Metamorphic rocks are rocks that have “morphed” into another kind of rock.

Now when you hear the expression “as solid as a rock”, you’ll know just how solid rocks really are. Challenging popular notions, such as the “solid as a rock” expression, make great science experiments. This one will interest a lot of people and teach them about the elements of our planet Earth.