A highly-etched Navegadora Mine spessartine, with recrystallization patterns. This thumbnail-sized crystal is a neat shape and exhibits dodecahedral-crystal face angles in its crystal surface patterns. This crystal glows deep red when strongly lit from behind (for example with a phone light). In excellent condition, a couple of tiny chips on the backside.
From the John S. White Collection – he had a few of these and studied them in connection with the article discussed below.
A word about the photographs and appearance of this specimen. This Navegadora spessartine can look different in different lighting conditions. The photographs here are meant to convey the lustre, the surface detail, the superb internal colour when well lit from behind, and also the dark appearance in lower light conditions. When looking at this specimen under modest light, it is dark red. Examined with light from behind, this crystal is intense glowing red.
About these Spessartines
These spessartines are from the famous March 2003 pocket at the Navegadora Mine. The Navegadora Mine exploits a pegmatite and produces feldspar for commercial purposes – It is not mined for specimens, and this pocket was unique. In an article in Rocks and Minerals (“Spessartine from the Navegadora Mine, Minas Gerais, Brazil” Vol. 84, Jan-Feb 2009) author John White discusses how these spessartines formed. While etching was involved, the specific mechanism that resulted in the final forms of these etched crystals remains a mystery.