Chalcoalumite
Araya, Aga city, Higashi-Kambara county, Niigata pref., Japan
Field of view: 10 mm. A crust of chalcoalumite. The reniform pale blue crust is chalcoalumite overlying the quartz surface. The brown parts are limonite crusts.
Recovered from an open space of a quartz vein in a meteoric oxidation zone of a moderate-temperature hydrothermal deposit associated with rhyolite.