This week, we have been investigating the properties of different types of rocks: sandstone, chalk, limestone, basalt, clay and granite. We decided to test the permeability, the durability, the hardness and the density of each rock? To test these properties, we had to do the following:
- drop small, droplets of water onto the rock to see if the water is absorbed by the rock or if it runs off. If the water is absorbed, the rock is permeable. If the water runs off, it is impermeable.
- use a coin to scratch a mark into the rock. If it’s easy to make a scratch, we can conclude that it’s not a durable rock. If it’s difficult to make a mark, we can conclude that it is very durable.
- Rub the rock in between both our hands. If small grains of the rock rub off on our hands, it’s not a hard rock. If no grains of the rock rub off, it is a hard rock.
- Drop the rock into a jug of water to see if it floated or sank. If the rock sank, it is high in density. If it floated or sank slowly, it is low in density.
We tested each of the rocks and used the results in our tables to create conclusions and make direct comparisons between the rocks. For example, we could conclude that the hardest rocks were basalt and granite, whereas the least durable rocks were clay and chalk.
