Franckeite - image 1
Franckeite - image 2

Franckeite

Unknown Owner
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This specimen is over 60 years old and was part of one of the best finds of the material right after the end of WWII. Only a handful of good specimens made their way to the United States, and well crystallized are few and far between. This is one of the rarest sulfosalts in the world. This specimen is a very rich, very rare, crystallized specimen of the triclinic lead, tin, iron, antimony sulfosalt Franckeite consisting of small bladed crystals forming spherical aggregate. This species belongs to the only group of minerals that forms in naturally "round" or "cylindrical" shaped crystals. This piece was from Richard Kosnar's well known Bolivian Collection, and the label indicates that it was once in the collection of the father of Bolivian Mineralogy, Federico Ahlfeld.

Product details

SpeciesFranckeite
SizeMiniature
Dimensions3.9 x 3.3 x 2.8 cm
Added on10/23/2024

Known provenance

DateCollectorAcquisition price
08/2024Unknown OwnerNot disclosed
The ArkenstoneNot disclosed

Learn more

Mineral guide
Learn about Franckeite
, a rare micaceous lead-tin-antimony sulfosalt, forms layered rosettes and curved plates; Bolivian origin and texture make it collectible.
Franckeite
Regional guide
Franckeite from San José Mine, Bolivia
from the San José Mine is one of the classic Bolivian sulfosalt specimens: black to steel-gray, metallic, soft, heavy, and often built from curving blades and radiating rosettes rather than simple textbook crystals. The best pieces have a lively sheen that moves across the bent plates as the specimen is turned, giving an otherwise dark mineral a surprisingly sculptural presence. Collectors prize San José franckeite because it shows the species in displayable form—not merely as a massive ore constituent, but as rosettes, foliated aggregates, compact sprays, and curved, bladed crystals that express the mineral’s layered structure in the hand.