3.3: What Are the Physical Properties of Minerals?

What Are the Physical Properties of Minerals?

Identifying a mineral is a bit like playing detective. Minerals are identified by their physical properties. Physical properties Links to an external site. are assessed by using observational skills. Observe Figure 3.2: how would you describe the mineral in this image?

You might describe this mineral as being yellow, with a shine and a distinct shape. Each description is actually a physical property (yellow = color, shiny = luster, shape = crystal form). As we learn more about minerals, it is important to note all available physical properties. Certain physical properties are referred to as diagnostic Links to an external site.; this means they are useful in identifying a particular mineral by name. Those properties that are not diagnostic are still helpful, but often other properties are required for a proper identification. Color is a property that is frequently variable and should not be used as a diagnostic property. For example, quartz Links to an external site., an important rock-forming mineral, is available in a variety of colors; other properties would be necessary for an accurate identification. However, occasionally color can be helpful, as in the case of the mineral azurite Links to an external site.. Azurite (from azure) is always blue in color.

Assessing the “importance” of one property over another, requires hours of practice with the minerals and their properties. This helps develop a mental mineral database, which can be used for future mineral identification. However, this database is only as good as the time and energy spent to develop it; geology majors, take note! Below are details regarding each of the physical properties to help identify minerals.