Mineral names are based on mineral appearance, mineral chemistry, where the mineral is found, a famous scientist, or anything else deemed important by a mineral’s discoverer. The Commission on New Minerals and New Mineral Names of the International Mineralogical Association reviews proposed new names and descriptions and judges their appropriateness. The Commission also occasionally discredits old names. Absolute identification and classification of minerals require knowledge of their composition and atomic structure. Mineralogists must include such information when they submit names to the Commission for approval.
3.2 Halite crystals from the Great Salt Lake, Utah
Determining mineral composition and structure may require time and equipment unavailable to most mineralogists or to mineralogy students. Fortunately, we can use other methods to tell minerals apart. Differences in composition and structure lead to differences in appearance and in many other mineral properties useful for identification. For example, the mineral halite, shown here in Figure 3.2, is most easily identified by its cubic, often clear crystals, by its softness, and by its salty taste.
Most of the properties discussed in this book fall into two general groups: hand specimen properties, which are easily determined using typical mineral samples, and optical properties, which we can only see with specially prepared slides and a polarizing light microscope, also called a petrographic microscope. This chapter reviews hand specimen properties and discusses their use in identification. We cover optical properties in the next chapter.