Corkite crystals from Cercal do Alentejo, Santiago do Cacém, Setúbal, Portugal, Gerd Tremmel collection – small cabinet specimen as unique piece
This small cabinet specimen with Corkite crystals from Cercal do Alentejo, Santiago do Cacém, Setúbal, Portugal, originates from the Gerd Tremmel collection and represents a particularly attractive example of this rare phosphate mineral. The Corkite crystals occur as numerous fine yellow to golden crystals densely covering the dark, lustrous matrix, creating an intensely sparkling surface.
The crystals are clearly visible and form dense, evenly distributed crystal coatings across large areas of the specimen. The combination of the bright Corkite crystals and the dark, partly glassy matrix produces a very strong contrast and an exceptionally aesthetic appearance. The formation is typical for this locality and shows the mineral in a highly decorative form.
Geology & Origin
Cercal do Alentejo in the Santiago do Cacém area, Setúbal region, is known for secondary phosphate mineralization formed through weathering and oxidation processes. Corkite belongs to the alunite group and forms under oxidizing conditions in iron rich deposits. The fine, densely packed crystals typically develop as coatings on the matrix and are characteristic of this geochemical environment.