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Multispectral imaging of ore minerals in optical microscopy

Published online by Cambridge University Press:  05 July 2018

E. Pirard
E. Pirard*
Affiliation:
Université de Liège, GeomaC –MICA, Sart Tilman B52/3, 4000 Liege, Belgium
*
*E-mail: eric.pirard@ulg.ac.be
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Abstract

Multispectral imaging of ore minerals under the microscope is a logical extension of quantitative colour analysis and microspectrophotometric analysis of minerals. This paper describes, step by step, how the proper calibration of a scientific video camera can be performed in order to obtain precise reflectance measurements at each pixel within the field of view. After having reviewed the different sources of noise and aberration, practical formulae are presented that allow for the acquisition of a set of images at different wavelengths in the visible spectrum.

The advantage of using a multispectral image acquisition system based on narrow bandwidth (10 nm) interference filters is discussed and quantitatively compared to colour imaging using tristimulus (red, green, blue) filters.

Images taken from major sulphide parageneses are shown as examples of well contrasted multispectral images. Finally, the potential for automatic identification of ore minerals is discussed with reference to supervised multivariate image classification algorithms similar to those used in remote sensing. Additional comments on extending the principles for handling optical anisotropy and developing a multiradial imaging system are made.

Keywords

multispectral imagingore mineralsoptical microscopyreflectance measurementssulphide parageneses
Type
Research Article
Information
Mineralogical Magazine , Volume 68 , Issue 2 , April 2004 , pp. 323 - 333
Copyright
Copyright © The Mineralogical Society of Great Britain and Ireland 2004

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