EONS: A579 HUGE POLISHED SLICED AMMONITE, 8" -- 1¢ OPEN

Pricing & History

Sold for
Start Free Trial or Sign In to see what it's worth.
Sold Date
Source eBay

EONS: A579 HUGE POLISHED SLICED AMMONITE, 8" -- 1¢ OPEN DESCRIPTION: In comparison to Grade A ammonites, Grade B ammonites usually (but not always) have more variable coloring and/or minor cosmetic imperfections and/or missing chamber lines and/or more gray chambers (which is ancient seafloor sediment) and/or rougher exteriors. But for a large segment of folks, this makes them more desirable than the Grade A ammonites which tend to be single colored. Like my Grade A ammonites, this one was chipped out of the entombing rock, the fossilized barnacles removed, the outside then laboriously buffed, then it was sliced in half and polished by hand to a glossy finish. This gives us an inside look at the individual growth chambers and the story behind them: as the animal grew, it would extend the open end of the shell by adding a larger growth chamber, pull its body forward into the new chamber, and then seal the old one -- but not before evacuating the water from its old chamber. Thus, each time the shell got bigger by one chamber, the newly sealed chamber maintained neutral buoyancy. Unlike a fish, the ammonite had neither lateral fins nor an air bladder, so it needed the air-filled chambers to keep it from sinking to the bottom. Eventually though, when the animal died, it did sink to the bottom w it was covered by sediment which became rock after eons of high pressure and heat which occur miles below the Earth's surface. During that process, the individual chambers experienced different fates. The chambers that ruptured relatively immediately became filled with gray organic-rich sediment, which are time capsules of the ocean bottom at that time. Microscopic analysis shows tiny fossilized fish bone fragments, shell parts, coprolites, and other remains of life. But the chambers that did not rupture followed a different path. For millions of years these remained empty, but eventually calcium-rich ground water leached into the chambers and deposited its calcite within them. The most impermeable of these remained hollow and exhibit a crystal-lined surface. Those that were less resistant experienced a heavier water flow and were completely filled with water born crystalline deposits. The different colors occur as a result of the different chemical composition of the water at the time that the crystals were forming. For example, the local groundwater may have been calcite-rich 90 million years ago because the formation was close to a river that was carrying the material from newly formed mountains. Then perhaps 40 million years later plate tectonics had carried the formation further south w ground water contained different trace elements due to another set of geological circumstances. And so any chambers that were still hollow at this time, were impregnated with different groundwater that caused different colors and crystalline structures. This was a constant process and so this specimen carries evidence of its entire 110-million-year plate tectonic ride. This specimen will appeal to not only fossil collectors, but also to home or office decorators, appreciators of the very old, fans of the unusual, nautical aficionados, aquarium enthusiasts, science buffs, educators, and parents who want to encourage scientific interest within their children. GREAT GIFT IDEA! Give one half to a good friend or a significant other, and keep the other half. This way every time you glance at it you will be reminded of that person. Genus: Cleoniceras Age: Cretaceous (approx. 110 million years ago) Found: Majunga, Madagascar (the huge island off the southeast coast of Africa) Condition: Stabilized fractures and/or repairs are often present; please examine the close-up photos provided. Size: 8 inches measured horizontally -- the coin that we include for size comparison measures 1 inch (2.5 cm) Weight: 4 pounds for the pair (add 2.5 pounds to calculate the shipping weight) SHIPPING WITHIN THE US VIA UPS GROUND: $12 for professional packing labor... read more

Items in the Price Guide are obtained exclusively from licensors and partners solely for our members’ research needs.

Flag item for content or copyright

If this item contains incorrect or inappropriate information please contact us here to flag it for review.

If you are the originator/copyright holder of this photo/item and would prefer it be excluded from our community, contact us here for removal.