Auction Name: 2026 April 29 Nature & Science Signature® Auction

Lot Number: 72221

Shortcut to Lot: HA.com/8248*72221

"Gem" Ammonite Fossil in Matrix
Placenticeras sp.
Late Cretaceous
Bearpaw Formation
Alberta, Canada

Placenticeras is a Late Cretaceous Ammonite from the Bearpaw Formation of Alberta, Canada, a locality renowned for producing exceptional "Gem" Ammonites preserved within black Shale. This striking specimen, measuring 7 inches (18 cm) in diameter, is naturally embedded within its matrix, creating a dramatic contrast between the dark host rock and the colorful and iridescent shell. The exposed Ammonite displays an extraordinary spectrum of colors, green, gold, red, and flashes of blue and purple, arising from the preservation of the nacre as Ammolite. The placement within the naturally contoured Shale enhances both composition and visual balance, giving the specimen a sculptural, almost intentional presentation. With vivid color, excellent preservation, and obvious commanding visual presence, this specimen offers remarkable impact relative to its size and will serve as a compelling centerpiece in any room, environment, or décor.
Overall Measurements: 25.20 x 14.57 x 1.97 inches (64.00 x 37.00 x 5.00 cm)

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