The
banded nature of the quartz veins which form the Empire lode at the Golden Cross
mine, is perhaps their most striking feature. Petrographic studies show that
significant differences occur between the bands in terms of textures, quartz
grain size, calcite, adularia and kaolinite content, and the form, concentration
and mineralogy of sulfide phases.

The 18Oquartz values of
individual bands within the vein material range from 7.3-10.9. Calculations
show that the 18Oquartz values can be adequately
explained by temporal variations in the system temperature, boiling and/or
variations in the systems fluid/rock ratios.