This half size flat contains a diverse collection of secondary arsenate and phosphate minerals, with Philipsbornite as the characteristic main component. The specimens predominantly display yellow green to olive colored coatings and fine crystalline aggregates on matrix.
Crystalline formations are clearly recognizable on several pieces. The crystals typically occur as fine, dense coatings, crusts, or small botryoidal aggregates, giving the specimens a vivid and textured surface. Matte to slightly lustrous yellowish to greenish crystal coverings are typical, often associated with additional secondary minerals from the oxidized ore assemblage. The flat shown corresponds exactly to the offered collection.
Geology & Origin
The Grandview Mine in the Grand Canyon, Arizona, is a classic locality for secondary lead, copper, and aluminum arsenates formed within the oxidation zone of uranium and copper bearing mineralization.
Philipsbornite forms there as a secondary mineral through the weathering of arsenic bearing primary ores in the presence of lead and aluminum. The exceptional geochemical environment of the deposit led to the formation of numerous rare arsenate species, making the Grandview Mine one of the most important localities worldwide for this mineral group.