The mineral crystallizes here in bright yellow-orange transparent crystals of textbook shape, sub-mm but eye-visible, presented nicely on underlaying tufts of acicular Uranophane. Named after a prominent Belgian, who at the time were the leaders in mineralogy of this region as they helped develop it, this is a very rare specimen of billietite because of the sheer richness of the piece. Usually we see this mineral as specks on other minerals, in a limited coverage. Here, many crystals of sharp billietite, sub-mm but eye-visible, sit perched on acicular Uranophane needles covering a large display face! From the prominent radioactives collection of Alain Caubel, of France.