“Reflected light digital image in air of allophane (light grey with some orange internal reflectance) showing the very typical shrinkage cracks due to dehydration. The shrinkage cracks are subsequently filled with goethite (g). Other inclusions are quartz (qu) and krut’aite (k). Width of image 1mm.
For further explanations see reference:
Günter Grundmann and Hans-Jürgen Förster (2017): Origin of the El Dragón Selenium Mineralization, Quijarro Province, Potosí, Bolivia. Published in: MINERALS 2017, 7, 68; doi: 10.3390/min7050068
G. Grundmann photo.