Columbite-Tantalite pseudomorph after Fluornatromicrolite (incredibly rare and fine)

Item Description

A magnificent nearly large cabinet sized display specimen from the famous Dara-i-Pech locality in Afghanistan. Only a handful of these were ever recovered, and I am confident in saying that this one is the finest example we've ever offered in the auctions. The specimen featuring several, sharp, well-formed, lustrous gray-brown octahedral crystals of what was formerly Fluornatromicrolite but has been pseudomorphed by Columbite-Tantalite! I can't remember another instance anywhere else in the world where this specific pseudomorph / replacement has been reported. Not only is this a large and showy specimen, but the quality of the pseudmorphs is outstanding, as several of them are as sharp and lustrous as I've seen. The largest crystal measures 1.6 cm. A few of the crystals are broken, but in this case it actually provides a bit more information about the replacement taking place. If you look closely, you can see a bit of a reddish hue, which is almost a sure indicator of the presence of maganese, meaning that this is either Columbite-(Mn) or Tantalite-(Mn) replacing the Fluornatromicrolite crystals. The matrix is a combination of Albite. Muscovite and Quartz, creating a wonderful contrast against the pseudomorphs. Fluornatromicrolite is a rare Na-Bi-Ta oxide, a member of the Pyrochlore Supergroup, and pseudomorphic material like this is incredibly hard to find on the market. Valued at $5,000 in the inventory for the size, quality and immense rarity of the material.