Potassium Alum (chromium-bearing) (synthetic)

Ex. Bill and Anne Cook
Small Cabinet, 7.1 x 6.7 x 6.3 cm
Start Time: 01/11/2024 8:00:00 pm (CST)
End Time: 01/18/2024 6:45:00 pm (CST)
Auction Closed
Winning Bid: $260

Item Description

A really attractive "geode" comprising crystallized Potassium Alum (with chromium content according to the label) grown in Germany. The entry on Wikipedia states, "Potassium alum is now produced industrially by adding potassium sulfate to a concentrated solution of aluminum sulfate. The aluminum sulfate is usually obtained by treating minerals like alum schist, bauxite and cryolite with sulfuric acid. If much iron should be present in the sulfate then it is preferable to use potassium chloride in place of potassium sulfate This substance is an acidic salt compound used as a primary standard for acid-base titrations and as a buffering agent." This is the ONLY crystallized example we've ever had to offer, and it's quite showy small cabinet featuring dozens of sharp, lustrous, gemmy, crystals, with a captivating saturated reddish-purple hue, free of matrix. The underside of the specimen shows a distinct green hue (probably from the chromium content). The largest crystal measures 1.3 cm. No major damage that I can find. The piece comes with a label detailing how the material is grown, and please note that it has been sprayed with acrylic in order to preserve the crystals.
From the synthetic mineral suite of William ("Bill") (1927-2006) and Anne (1928-2021) Cook of Cleveland, Ohio (#5586). This husband and wife duo were actively involved in the mineral world for many decades. Bill was a PhD geologist, and Anne was a mathematician, and they both were very serious mineral collectors. Bill served for many years as adjunct curator of mineralogy at the Cleveland Museum of Natural History, and Anne was inducted into the Micromounters' Hall of Fame on October 12, 2019. Both Bill and Anne, at various times, served as president both of the Mineralogical Society of Cleveland and of the Micromineral Society of the Cleveland Museum of Natural History. The rare barium lithium beryllium phosphate Wilancookite was named in their honor in 2015.

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Bidding History

Bid Amount Bid Time
$260 01/18/2024 6:10:47 am (CST)
$250 01/18/2024 6:10:31 am (CST)
$245 01/18/2024 6:10:31 am (CST)
$205 01/18/2024 6:10:14 am (CST)
$195 01/18/2024 6:10:14 am (CST)
$131 01/14/2024 9:11:52 pm (CST)
$121 01/14/2024 9:11:52 pm (CST)
$90 01/14/2024 6:16:32 pm (CST)
$80 01/14/2024 6:16:32 pm (CST)
$70 01/14/2024 10:15:12 am (CST)
$60 01/12/2024 6:52:39 pm (CST)
$50 * 01/12/2024 6:52:32 pm (CST)
$50 * 01/12/2024 6:52:32 pm (CST)
$35 01/12/2024 6:52:23 pm (CST)
$30 01/12/2024 6:52:23 pm (CST)
$20 01/12/2024 6:52:13 pm (CST)
$15 01/12/2024 6:52:12 pm (CST)
$10 01/12/2024 5:34:58 am (CST)
* Proxy Bid Battle: In the event of two customers inputting matching proxy bids, the leading bid goes to the earliest of the two proxy bids. Tie winners are shown in bold.