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Minerals and the crystalline state
Minerals and the crystalline state

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3 Physical properties of minerals in hand specimen

Physical properties, such as colour and density, are those that can be observed without causing any change in the chemical composition of a specimen, whereas chemical properties determine how a substance behaves in a chemical reaction. Many of the physical properties of minerals can be predicted from a detailed knowledge of their crystal structures, which can be obtained by various analytical techniques. Alternatively, physical properties can be used to infer particular aspects of a mineral's internal structure.

Several physical properties of minerals can be readily observed in hand specimen and can be used for recognising and distinguishing different minerals. In this course you will do this using the Digital Geology Kit [Tip: hold Ctrl and click a link to open it in a new tab. (Hide tip)] , which is introduced in the next activity.

Activity 1 Introduction to the Digital Geology Kit

Timing: Allow about 40 minutes.

Task 1

Begin by watching Video 1 to familiarise yourself with the functionality of the Digital Geology Kit. (You will need to view it in 'Full Screen' mode in order to see in detail the various tools and features.) Then answer the associated questions.

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Video 1 Introduction to the Digital Geology Kit.
Interactive feature not available in single page view (see it in standard view).

Question 1

Select the specimen 'Variety amethyst' from the 'Quartz' list of minerals in the Digital Geology Kit. How long is the amethyst crystal on the far left? Measure it using the graticule.

Answer

It is about 16 mm. Note that there are large divisions on the graticule every 10 mm.

Question 2

Now go to 'Red crystals in gneiss' in the 'Garnet' list. Go to coordinates X = 1860, Y = 930. (Note that, hereafter, the X and Y labels will be omitted on all coordinates, e.g. this point would be '(1860, 930)'.) Is any red garnet visible at the point denoted by the cross hairs?

Answer

No, garnet is not visible at this point; only a white mineral is visible at the stated coordinates.