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    Placenticeras intercalare
    Bearpaw Formation, Southern Alberta, Canada
    A huge and dazzling example of these highly sought-after specimens, this extremely bright, colorful ammonite flashes across its entire surface on both sides with a gorgeous combination of fiery iridescent red, green, orange and gold, with hints of the extremely rare blue-purple. These beautiful shimmering colors were naturally created by the combination of millions of years of compression and the mineralization of iron, copper and silica which precipitated from the bentonite sediment of volcanic ash. In most cases elsewhere, the aragonite-rich nacre (mother-of-pearl) of the ammonite's shell lining is pseudomorphously replaced by calcite or pyrite. In the Bearpaw Formation, stretching over parts of Montana, Alberta and Saskatchewan along the eastern slopes of the Rocky Mountains, however, the ammonite's shell becomes tainted with trace elements such as manganese, strontium, titanium, barium and others, manifested in the dazzling colors displayed here. The resulting gemstone is called Ammolite, although it is known to the Káínawa, or Blood Tribe, of southern Alberta as Aapoak ("small, crawling stone") and to the Blackfeet Indians of Montana as Iniskim ("buffalo stone") and has long been believed to have amuletic powers of use in healing and in attracting buffalo. Practitioners of feng shui and crystal metaphysics value it as the Kirin stone or seven-color prosperity stone, and believe it to be useful in detoxifying the body and promoting energy flow and prosperity. In 1981 it was accorded gemstone status by the World Jewelry Confederation; unlike other gemstones, however, whose brilliance is caused by light reflected from the surface, the shimmering and ever-changing colors of ammolite are the result of light refracting through and rebounding from the thin platelets of aragonite in the shell. Like amber and pearl; ammolite is one of very few biogenic gemstones. This is an unusually fine and large example, displaying good three-dimensionality to over half of its size (most specimens are found almost entirely flattened) and measures 21½ inches in diameter.

    Condition Report*: Condition report available upon request.
    *Heritage Auctions strives to provide as much information as possible but encourages in-person inspection by bidders. Statements regarding the condition of objects are only for general guidance and should not be relied upon as complete statements of fact, and do not constitute a representation, warranty or assumption of liability by Heritage. Some condition issues may not be noted in the condition report but are apparent in the provided photos which are considered part of the condition report. Please note that we do not de-frame lots estimated at $1,000 or less and may not be able to provide additional details for lots valued under $500. All lots are sold "AS IS" under the Terms & Conditions of Auction.

    Auction Info

    Auction Dates
    June, 2011
    12th Sunday
    Bids + Registered Phone Bidders: 2
    Lot Tracking Activity: N/A
    Page Views: 3,847

    Buyer's Premium per Lot:
    19.5% of the successful bid (minimum $14) per lot.

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