14: Mineral Descriptions

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Rhodochrosite, quartz, chalcopyrite, and tetrahedrite, from the Sweet Home Mine in Alma, Colorado; 5.2 cm across

Many Different Minerals

Mineral Identification . . .

Identifying unknown minerals can be easy or very challenging. An experienced mineralogist focuses on one or a few properties that are most diagnostic. Other people may wish to use some sort of systematic approach or key. Many keys can be found with a Google search, but my favorite is at the URL below. If you use it, be sure to answer all questions with yes or no; otherwise you may not get to the correct tables.

Link to mineral ID key (Plante, Peck & Von Bargen; 2003)

Geologists and mineralogists have described more than 3,000 minerals; most are exceedingly rare, and it is unnecessary and impractical to try to describe them all in this book. The links below in Table 14.1 take you to descriptions of about 180 individual mineral species. You can also use the navigation menu on the right-side of this web page to find different minerals.

The mineral descriptions in this chapter are arranged in order based on the classification scheme presented in Chapter 1; Table 14.2, below, summarizes it. Links in the table take you to different parts of the system. A brief introduction and tabulation of mineral species introduces each of the classes, subclasses, series, or groups.

About the photos . . .

Most of the photos in this chapter came from Wikimedia Commons or mindat.org. An especially large number are photos originally taken by Robert M. Lavinsky, Géry Parent, James St. John, and Didier Descouens; they deserve special acknowledgment. Credits for all photos except those that originated at the University of North Dakota are listed at the end of the chapter.

Many minerals have many different appearances. This chapter includes representative photos, but you should go to Wikipedia, Wikimedia Commons, mindat.org, or simply Google, if you wish to see all the possible varieties.

Be warned: professional mineral photographers like to take pictures of spectacular samples. These are not the kind of specimens you can expect to encounter unless you are very lucky or go to a museum, but they are the ones you are most likely to find in photographs on the web. However, the photos in this chapter were selected so they include both mundane and museum-quality samples.

This chapter contains descriptions of the most common minerals (but many of them are not very common), as well as descriptions of others that have economic importance. Other species are included if they have unique structures or chemistries, or demonstrate principles or properties not well represented by the common or economic minerals. Still others are here if they are useful indicators of geological environments and processes or if they can be used for practical purposes, such as radioactive age determinations.

The information given here is intended for students of mineralogy, so emphasis has been placed on those properties that best aid in practical mineral identification: hand specimen characteristics and, to a lesser extent, occurrences, associations, and optical properties. The mineral descriptions contain only brief discussions of atomic arrangements and crystal chemistry.