Realgar

Field of view: 5 mm. Realgar perched on orpiment. The short red prisms are realgar. The basement is covered with a crust of fine dark yellow orpiment crystals. The transparent yellow needles on the corner of the realgar crystal at the center are probably wakabayashilite.

Recovered from an open space of a realgar vein in a low-temperature hydrothermal deposit formed by a andesite dike in andesitic tuff breccia filling a caldera. Formed in the late Miocene (6 Ma).

Realgar from this location was described in 1932, and was designated the prefectural mineral of Gunma in 2016 by the Geological Society of Japan.