Offretite (rare zeolite)

Mont Semiol, Châtelneuf, Montbrison, Loire, Auvergne-Rhône-Alpes, France (Type Locality)
Ex. Dr. Vasco Trancoso
Small Cabinet, 5.7 x 4.3 x 4.3 cm
Start Time: 05/02/2024 8:00:00 pm (CDT)
End Time: 05/09/2024 6:45:00 pm (CDT)
Auction Closed
Winning Bid: $51

Item Description

A very hard to find specimen of the rare zeolite mineral, Offretite (named for the French professor Albert Offret). The species is rarely seen in good display quality specimens, but this is a fairly showy piece of the material featuring a vug filled with tiny radiating crystals of off-white colored Offretite, associated with minor crystals of the Phillipsite Subgroup. The piece is best seen under magnification, to best see the little crystals, but it does display quite nicely as it sits on its own without the aid of a base or clay. Additionally, the piece is from the type locality for Offretite, which makes it all the more desirable for a rare species.
From the collection of Vasco Trancoso, a medical doctor and prominent mineral collector from near Lisbon, Portugal ( He assembled his mineral collection over the course of 60 years, and built a fine worldwide display collection that we recently purchased. This piece is pictured on at

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Bidding History

Bid Amount Bid Time
$51 05/09/2024 11:01:39 am (CDT)
$46 05/09/2024 11:01:38 am (CDT)
$45 05/06/2024 6:10:42 pm (CDT)
$40 05/06/2024 6:10:42 pm (CDT)
$35 05/06/2024 6:10:33 pm (CDT)
$30 05/06/2024 6:10:33 pm (CDT)
$25 05/06/2024 2:03:20 pm (CDT)
$20 05/06/2024 2:03:19 pm (CDT)
$15 05/05/2024 6:56:33 pm (CDT)
$10 05/03/2024 10:53:08 am (CDT)