Denton Mine, Goose Creek Mine Group, Harris Creek Sub-District, Illinois-Kentucky Fluorspar Dist., Hardin Co., Illinois, USA

    One of the beautiful mysteries of chemistry is how a simple binary compound of Calcium and Fluorine can have so many different colors, much less forms. Take this specimen for example; there is a zone at the "base" of the specimen that is colored a luscious sky-blue with a smidgeon of purple. This cool blue state of affairs abruptly shifts to deep purple, and then it oscillates between light purple and dark purple. The mystery is why does it do this? The answer most frequently offered is this phenomenon is a result of an interplay between the crystal lattice and defects in the lattice caused by irradiation. In a few cases, it can also be a result of non-essential elements taking up residence in the same lattice (think Rare Earths, for example). The REAL answer is: We Don't Really Know ... the mystery is still there. In the two simple cubic crystals that make up this pair, the shift in intensity of color takes place 11 or 12 times before you get to the surface of the specimen, where growth has stopped. When backlit from the right direction those color bands become highly visible due to the great transparency of the piece. Luster is waxy to glassy thanks to extremely complex features being present on all major faces. Overall, condition is excellent with only minor chipping, chiefly near the base of the specimen. Both of the crystals measure around 2 inches (5 cm) across. This piece is accompanied by a custom labeled acrylic base.
    Overall Measurements: 4.74 x 3.2 x 3.82 inches (12.0 x 8.13 x 9.7 cm)

    Estimate: $30,000 - $35,000.

    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. 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.

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    Auction Info

    Auction Dates
    September, 2014
    28th Sunday
    Bids + Registered Phone Bidders: 0
    Lot Tracking Activity: N/A
    Page Views: 1,579

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