Hydroxylherderite (rare unique form)

Item Description

There are many localities in Brazil for Herderite (Hydroxylherderite), but typically the species forms individual crystals, and "clusters" are fairly rare. This piece has a truly unusual and unique form, as the thin crystals are intergrown to create rarely seen "rosette"-esque groups, free of matrix. I can't recall another piece quite like this, not only from Brazil but any locality. I honestly did a double-take, as I thought surely it can't be Herderite, it must be some kind of Feldspar, but I looked closely, and the crystals are clearly Hydroxylherderite. The color is a gentle beige-yellow hue, and the crystals are sharp and lustrous when you view them up close. Overall, the piece is in very good condition, with only a small amount of roughness around the exterior edges when the piece was removed from the pocket. If you collect pegmatite minerals, this is something that is almost singular in my experience, and you're not likely to see another like it any time soon.
From the collection of Gerry Morvell. You can actually see this piece posted on mindat (from over 20 years ago) at the following link: https://www.mindat.org/photo-3406.html