witherite — species of mineral; data; faceted specimens exist …
wulfenite — species of mineral; data; faceted specimens exist …
wurtzite — species of mineral; data; faceted specimens exist …
xenolith — a rock fragment which becomes enveloped in a larger rock during the latter’s development and hardening …
Xinshan jade — a synonym of serpentine jade …
xonotlite — species of mineral; data; faceted specimens exist …
zebra stone — a rock; see zebra stone in ‘Classification’ …
zektzerite — species of mineral; data; faceted specimens exist …
zincite — species of mineral; data; faceted specimens reported …
zircon — species of mineral; see zircon in ‘Classification’ …
zoisite — species of mineral; see zoisite in ‘Classification’ …