:Locality: Lengenbach Quarry, Binntal, Wallis, Switzerland Size: 1.7 × 1.5 × 0.8 cm Description: A really amaizing specimen of this rare talium species: imhofite. Bronze colored "book shape" tabular crystals perfectly disposed very aerial and contrasting with the white sugar dolomite matrix. It is acompanied by prismatic elongated brilliant red hutchinsonite crystals and yellowish orpiment. Lengenbach Official Number: L-22322. Find in 1990 (27 years ago!). The number of confirmed imhofite specimens until 2002 was only 120, and later grew to only 172 (Faszination Lengenbach, 2008). Lengenbach is the Type Locality and only two more localities are known worldwide. — Photo: Joan Rosell , from rosellminerals.com · CC BY-SA 4.0
Imhofite
Imhofite is an IMA-recognized mineral species in the sulfosalt class, with the chemical formula Tl₅.₈As₁₅.₄S₂₆.
It crystallizes in the monoclinic crystal system (space group P2_1/n).
Key properties: Mohs hardness 2; specific gravity 4.39.
IMA symbol Imh, IMA status: approved, named in 1965.
Hydrothermal in origin.
It is found associated with Realgar, lead sulfantimonides.
The mineral was named to honor Josef Imhof (1902–1969), professional mineral collector of Binn, Switzerland.