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Department of Mineral Sciences

Izalco Volcano

The cathodoluminesce (CL) laboratory of the Department of Mineral Sciences is equipped for cathodoluminescent imaging and spectroscopy of geologic materials. The lab is equipped with an ELM-3R Luminoscope and MacPherson .2meter scanning monochromator with Macpherson 789A controller. Images are captured using an Olympus Magnafire CCD camera. Recently, a vibration isolation table has been added for improved high magnification imaging.

A broad beam of accelerated electrons is deflected onto the surface of a polished mineral mount or rock section. Outer shell electrons in the specimen are \"excited\" and emit energy with wavelengths that correspond to visible light (as well as the UV and near IR) upon relaxation. These colors can be digitally imaged to map out the often highly detailed growth history of minerals. In addition, the precise wavelengths emitted from a sample can be obtained with the spectroscopy system. This visible light spectrum allows one to more precisely identify individual components of luminescence.

Cathodoluminesce imaging

Dr. Michael Wise and Cathe Brown imaging a complexly zoned apatite from Black Mountain, Maine.
CL images of pegmatite by Jennifer Maloney. Left image shows zoning in blue and maroon potassium feldspar with green albite and brown quartz. Right image shows replacement of albite (green) by mica (red). Both samples are from Black Mountain, Maine. Field of view is 3.5 mm wide.
Images captured by Rabiyah Carter of Guatemalan Jade sample MVE02-77-2. Left image is in plane light, right image is CL of same area. Image width is 1.8 mm.
Petrified wood images by Jocelyn Johnson. Left images in plane light. Right images are CL. Upper sample is apatite, upper Devonian, New York. Lower sample is chalcedony, Eocene, Wyoming. Width of all images is approximately 1.8 mm.

Corundum standard

Image at left shows luminescence of mineral standards. At right a CL image shows corundum standard used for calibration of the spectrometer. Width of image is approximately 2mm.
The spectrum of the corundum standard.

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