These rare crystals, of this quality, were found just ONCE in the mid 1980s and brought to market by John Whitmire in a single offering at the Tucson show. A choice example remains today one of the hardest items of Mexican material to obtain. This piece is "just a thumb size" perhaps, but what a fine one! Super crystals to 1.5 cm, top quality, on matrix no less! I have never seen as nice a matrix thumbnail of this material for sale. Formerly in the collection and with label of Willard Perkins, the collector who invented the so-called "Perky Box" for thumbnails (it also has microcrystals of lotharmeyerite. examine the specimen very CLOSELY with a stereo scope and see if you see any tiny dark red needles scattered on the black matrix. That would be lotharmeyerite - Mapimi is the type locale and it was found with purple adamite).