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Cathodoluminescence and Rare Earth Minerals Exploration

Added 3/12/13

These CL photos are from the special issue of Elements, dedicated to Rare Earth Elements. Volume 8, No. 5, October 2012.

Cathodoluminescence is a very important tool in the study of rare earth minerals. Dr. Anthony N. Mariano has pioneered its use for many years and especially when coupled with spectral measurements of the CL emission. Elsewhere on this web site photo gallery is an example of the spectra of CL emissions from a rare earth-doped synthetic calcium fluorite.

The first example is a CL image of xenotime and associated minerals in peralkaline granite.

Here is a labeled version below. Click on the photo to see a larger version.

This first example is from the paper by:

Chakhmouradian, A. R. and Zaitsev, A. N., Rare Earth Mineralization in Igneous Rocks: Sources and Processes. pp 347-353. Figure 5C.

Second example is from Mariano, A. N. and Mariano, A., Jr. , Rare Earth Mining and Exploration in North America, pp. 369-376. Figure 3C.

This is a Cathodoluminescence micrograph of Sm3+ - activated apatite (light pink) in a dolomite carbonatite matrix (field of view = 2.5 mm).

All three photographs were taken by Dr. Anthony N. Mariano.

Dolomites, Early Ordovician

Added 9/21/12

Dolomites from the Arbuckle Group from the deep subsurface in Kansas

(Photo set and description provided by Dr. Greg Ludvigson)

Authigenic Feldspar

Authigenic feldspar in a carbonate rock. The detrital feldspar is the bright blue grain in the center and the authigenic feldspar is the non-luminescing black region surrounding it.

This is one of the very first examples showing the usefulness of CL in studying authigenic feldspars and distinguishing them from their detrital counterparts.

This photo was originally taken by Dr. Miriam Kastner when she worked with Dr. Siever at Harvard in 1972. Dr. Kastner is now a Distinguished Professor of Earth Sciences at Scripps Institute of Oceanography. Recently, she was awarded the prestigious Francis P. Shepard Medal. By SEPM.

More On Cathodoluminescence and Rare Earth Minerals Exploration

Added 1/13/14

Cathodoluminescence photomicrograph of carbonatite with manganoan calcite (orange-red), primary apatite (purple), hydrothermal apatite (yellow-green), and ferric-iron-bearing orthoclase (pink-red, bottom of image). Horizontal dimension of photo is 1.59 mm. 10 kV, 0.5 mA beam. (Courtesy of Adrian Van Rythoven, Rare Element Resources, Inc.)