The Sant Fost willemite appears in small crystals with a pseudohexagonal prismatic habit (twinned), with striated faces. All of them are sub-millimetric in size and form druses of crystals with a resinous or adamantine luster, with colors ranging from dark brown to honey-yellow, or they may appear colorless and transparent. In Sant Fost the willemite appears associated to a sphalerite vein together with silicates (quartz and clays), calcite, fluorite, and baryte. Willemite is fluorescent under SW-UV light. Very unusual locality for the species.

Size: 3.8 x 1.7 x 0.9 cm.
Found in 2021.

Con análisis / With analytical report
Fluorescent under short wave UV