Minerals of the Tower Hill Quarries, Snohomish County, Washington, USA (washingtonminerals.com)
Mount Persis Andesite - Tertiary. Hydrothermally altered andesite, varying in color from gray (less altered) to yellow, red and brown where heavily altered. Voids created by faulting and brecciation have been partially/completely filled by hydrothermal mineralization.