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

This free course is available to start right now. Review the full course description and key learning outcomes and create an account and enrol if you want a free statement of participation.

Free course

An introduction to minerals and rocks under the microscope

2.2 Minerals and polarised light

A beam of light from an ordinary source, such as the Sun, consists of electromagnetic waves that vibrate in all directions at 90° to its direction of travel (Figure 28). Such a beam of unpolarised light can be modified to constrain its vibration direction to a single plane by using a polarising filter (a transparent sheet branded as Polaroid). Light transmitted through this polarising filter (or polariser) is called plane-polarised light (Figure 28). The direction of polarisation is the permitted vibration direction of the material. This effect is the basis for various observations using the polarising microscope that are important for identifying minerals.

Figure 28 The production of plane-polarised light using a polarising filter.
S276_1

Take your learning further

Making the decision to study can be a big step, which is why you'll want a trusted University. The Open University has over 40 years’ experience delivering flexible learning and 170,000 students are studying with us right now. Take a look at all Open University courses.

If you are new to university level study, find out more about the types of qualifications we offer, including our entry level Access courses and Certificates.

Not ready for University study then browse over 900 free courses on OpenLearn and sign up to our newsletter 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 prospectus