Here's a nice looking "whopper of a Manganite group." With an estimated value between $150,000 and $175,000, it has an opening bid of $75,000. It's one of over 300 gems and minerals being auctioned by Heritage.
Ilfeld, Nordhausen, Harz, Thuringia, Germany
If it wasn't for the Ilfeld Manganese mines, Manganite would be relegated to back row status in the Pantheon of Fine Minerals. Fortunately, Manganite was rescued from obscurity by the brilliant, midnight-black crystal groups found in this part of the Harz Mountains. Of the various Manganite groups known, the one seen here is arguably in the top 5. Single crystals run riot over the upper surface of a massive Manganite/Pyrolusite matrix, with thin layers of the original wall rock visible on the absolute bottom of the specimen. Many of the crystals are over one inch, and some are much larger: up to 1.88 inches (4.74 cm). At better than 6.5 inches (16.5 cm) in length, this is not a small example of this mineral; it is a whopper of a Manganite group. The condition of this 'black beauty' is absolutely pristine with no visible damage. As befits a world-class specimen of Ilfeld Manganite, it comes with a custom acrylic base.
Overall Measurements: 6.49 x 3.34 x 2.65 inches (16.5 x 8.5 x 6.74 cm)
I've got my eye on this hunk of heulandite on chalcedony, which "looks like Godzilla as a hockey goalie," and has a current high bid of $1.