"Store Didoni" Collection, Macherio (MB)

Discovered in 1962 in Namibia (where the type locality is located, near Outjo) and also found in China (Hunan Province), it is named after the South African prospector Sid Pieters. It forms through pseudomorphic silicification of crocidolite bundles (blue asbestos, a fibrous sodium amphibole), whose filaments are then fractured by tectonic events and re-cemented by silica in a brecciated process, resulting in a chaotic, swirling chatoyant effect in shades of blue, gold, and reddish hues. Hardness 6.5–7 on the Mohs scale (dominated by quartz), with a density slightly higher than that of pure quartz (3.3–3.6 g/cm³) due to iron residues.

Highly prized by collectors and gemstone artisans for the unique and turbulent pattern of each specimen, which makes it one-of-a-kind; widely used for cups, spheres, and finely carved decorative objects; in crystal therapy, it is associated with vision and transformation.