Pharmacosiderite

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The world's finest Pharmacosiderite was discovered several centuries ago in the Wheal Mutterel section of what later became Wheal Gorland mine. An extremely detailed account of that occurrence was published by William Phillips in 1811. This stunningly beautiful specimen from the A.G. Moss collection (no. M109) is documented simply as from the St. Day area, but its richness far exceeds that of any other occurrence than Wheal Mutterel/Gorland. Its colour is the most desirable bottle-green with a supremely glossy lustre, and the crystals, cubes up to 2.5 mm on edge, completely encrust one side of the specimen in an area 4.5 x 3 cm. If you look carefully there is some contact damage to the highest crystals, but this is an extremely showy example of this rare iron potassium arsenate species. The matrix is gossanous Quartz veinstone with some relict Arsenopyrite.