Rocks and Minerals By Kenrick Leiba
3 Kinds of Rock • Igneous – rock that has melted and re-solidified. • Sedimentary – Formed from sediments that have been compacted and cemented together. • Metamorphic – Rock that has been changed by heat and pressures.
Some revision on mixtures, compounds and elements • An element has one kind of atom • A compound has two more kinds of atoms in a fixture ratio • A mixture is mix of two or more substances that are NOT bonded.
Most common Elements in the Earth’s crust • oxygen-46.4% • silicon-28.2% • aluminum-8.2% • iron-5.6% • calcium-4.2% • sodium-2.4% • magnesium-2.3% • potassium-2%
How do Rocks differ from minerals? • A mineral has a known chemical composition with a fixed ratio of elements. (could be an element or compound) • Rocks are made up of two or more minerals. • Therefore a Rock is a solid mixture of minerals the way cake is a mixture of eggs, flour, water etc.
How to identify Minerals • Look at the following slides. Each shows several differ same samples of the same mineral. • What feature might be most useful for identification. What problems might you encounter.
Examples of minerals • Quartz
Some examples of rocks • The following are some examples of different types of rocks.
Most common minerals • On the surface of continental crust: Quartz • In the whole crust: Feldspar • In the mantle: Olivine