Gold

Field of view: 5 mm. Gold associated with pyrite. The yellow grain at the center is gold. The surrounding massive black host is quartz containing fine sulfide minerals, so called Ginguro (Silver black).

Recovered from a quartz vein in a low-temperature hydrothermal Au-Ag deposit associated with tholeiitic andesitic-basaltic tuff breccia in an oceanic arc subjected to prophylitization alteration. Formed in the early Pleistoene (4.0 Ma).

Gold from this location was described in 1982.

Field of view: 30 mm. Gold ore. The black band at the right is the Au- and Ag-bearing sulfide zone, Ginguro (Silver black). The white parts are quartz, and the purple part at the left is amethyst perched on quartz. The left side of the specimen is the vein center, and the right side is the vein wall. The banded structure of the vein is as follows from the host side (right) to the center (left): Impure quartz, Au-Ag-Sulfide band (Ginguro), transparent quartz, amethyst.