A superb chalcosiderite specimen exhibiting large vug (and smaller ones!) with excellent, vitreous, dark apple-green chalcosiderite rosettes to 1.5mm set upon and nicely accented by a black-brown carpet of what appears to be goethite. Now for the rest of the story! The reverse side shows thick coverage of densely grouped chalcosiderite crystals coating over half of the surface! A great old-time specimen of this uncommon hydrated copper aluminum iron phosphate! Ex. Frank Avray Wilson collection with label.