An introduction to minerals and rocks under the microscope
An introduction to minerals and rocks under the microscope

Start this free course now. Just create an account and sign in. Enrol and complete the course for a free statement of participation or digital badge if available.

Free course

An introduction to minerals and rocks under the microscope

3.8 Summary of Section 3

  1. The most important rock-forming minerals on Earth are silicate minerals, composed of silicon, oxygen and a variety of metal cations. The basic building block of silicate minerals is the SiO4 tetrahedron. However, what defines the structural variety and with it a range of properties of silicate minerals is the ability of SiO4 tetrahedra to link together, or polymerise, by sharing oxygen atoms in different ways and in different proportions. Increasing polymerisation increases the silicon to oxygen ratio to reach that of quartz, which has a fully polymerised structure.
  2. Silicate mineral groups are built of different forms of three-dimensional structure: isolated units, chains, sheets and frameworks, with a corresponding increase in the silicon to oxygen ratio from 1 : 4 to 1 : 2. These three-dimensional structures are mostly bound together by metal cations. The crystal structures of these mineral groups have important consequences for the physical properties of the minerals.
  3. The main silicate mineral groups covered in this section, for which the chemistry, structure, occurrence and properties are considered, are those with isolated SiO4 tetrahedra (olivine and garnet), the chain silicates (pyroxene and amphibole), the sheet silicates (micas and clay minerals) and the framework silicates (quartz and feldspar).
  4. Major non-silicate mineral groups include the carbonates, oxides and sulfides. Carbonates are an important part of the carbon cycle whereby carbonate minerals are precipitated from seawater, often as skeletons of organisms, and deposited on the sea floor. Oxide and sulfide minerals can be economically important as sources of metals when they are concentrated as mineral deposits.

Take your learning further371

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has 50 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses372.

If you are new to university level study, we offer two introductory routes to our qualifications. Find out Where to take your learning next?373 You could either choose to start with an Access courses374or an open box module, which allows you to count your previous learning towards an Open University qualification.

Not ready for University study then browse over 1000 free courses on OpenLearn375 and sign up to our newsletter376 to hear about new free courses as they are released.

Every year, thousands of students decide to study with The Open University. With over 120 qualifications, we’ve got the right course for you.

Request an Open University prospectus371