Caledonite is great rarity for the Tsumeb Mine, and many specimens are actually mislabelled turning out to be Brochantite with Linarite, or Serpierite. This specimen probably came from the outcrop (the green hill) as Caledonite was only recorded as coming from here. The outcrop was worked out by the early 20th century, and the age of the specimen is supported by the accompanying Dr. F. Krantz label of about the same era (very few specimens of any kind survived from the outcrop workings). The Caledonite forms bright blue crystalline masses filling voids in a matrix of glassy Cerussite. The Caledonite is associated with blue Linarite and green crystal sprays of Malachite embedded in the Cerussite. A real rarity from the Tsumeb Mine.