Chalcosiderite

Rich druses of dark emerald-green crystals of Chalcosiderite are one of the signature minerals of the famous Wheal Phoenix mine at Minions near to Linkinhorne in Cornwall.  This rare copper-iron phosphate occurs as sub-mm crystals richly lining wide open vugs and porous cavities within a Quartz gossan matrix, some of the crystal-lined vugs attaining 3 x 1.5 cm in area.  Sparsely scattered over some parts of the specimen are near-perfect orange-brown spheres to about 1 mm diameter; likely to be Dufrénite, but not confirmed as such.  This beautiful and rich specimen would look good in a cabinet display, being a fine example from Wheal Phoenix, part of the Cornwall Great United Mines sett.