Reflected light optical microscopy, or epimicroscopy, is one of the oldest techniques of modern mineralogy. At a relatively low capital cost, it is also very resourceful, and the analytical choice for the identification of most ore minerals._x000D_
In ore mineralogy, reflected light optical images have the potential to overcome the main limitation of backscattered electron images from scanning electron microscopes, namely contrast of mean atomic number below the spectral resolution of the backscattered electrons detector. This is the case for relevant ores, like iron (haematite-magnetite) and copper-zinc ores (sphalerite-bornite), but for both cases the pairs of minerals are easily discriminated in reflected light._x000D_
The improvements in optics and electronics also made microscopy a powerful source of digital images, suitable for automated analysis for minerals processing, as the determination of liberation spectra. The drawback, however, has always been the impossibility to recognise the transparent minerals, which account for most of the gangue phases in ores, from the embedding resin, usually epoxy._x000D_
In order to determine if there was any possibility to separate quartz from epoxy resins, reflectance spectra have been acquired for quartz and some commercial epoxy resins (Araldite, Buehler's Epothin and Epocolor, Araldite spiked with fluorochrome from Struers), from 380 to 720 nm in 5 nm intervals._x000D_
Reflectance of quartz and epoxy is very similar over the whole visible light range, and varies from 4.5 to five per cent. Epocolor, a red-dyed epoxy, reflects slightly more above 560 nm, as does Araldite spiked with the fluorochrome from 460 to 570, but for both the reflectance is still very close to that of quartz, under 5.1 per cent._x000D_
This data set is final, and precludes the application of reflectance in light optical image analysis for assessment of liberation, phase quantification, or any other signal that requires separation of resin from transparent minerals.