- Siglo Veinte Mine (Siglo XX Mine; Llallagua Mine; Catavi), Llallagua, Rafael Bustillo Province, Potosi Department, Bolivia
- Small Cabinet, 5.2 x 3.6 x 1.4 cm
This specimen is a very well crystallized, outstanding blue color, very rare specimen consisting of radiating crystal aggregates of Vauxite on a thin layer of minor clay matrix. These crystals of Vauxite show the most electric neon blue color that I've seen for the species, but it appears that the rich color is actually due to a micro coating of transparent Quartz on top of the Vauxite. This piece is from a new find at the type locality for this material which was originally discovered along the Contacto and San Jose veins in this mine and first described by Sam Gordon and Mark Bandy.