Hydroxylherderite (ex Rolando Gioia Collection)

Item Description

This piece came with a small scrap of paper that said "Herderite" with no given locality. I'm not 100% certain that it is indeed Hydroxylherderite or any species of Herderite as I haven't seen anything quite like it. The main crystal measures 3.7 cm long and has an almost "rusty" reddish-brown hue. It has sharp, well-formed faces and sits beautifully on the underlying feldspar and mica matrix. From the collection of Rolando Gioia (a contributor to new definitive book on Brazilian minerals: "Minerais e Pedras Preciosas do Brasil").