The Whitesail Mountains in northwestern British Columbia are one important source for fine opals, found in vesicles in a basaltic rock - under alpine conditions. At this locations agates do occur - and these nodules may contain opal too.
The agates from this location are only weak banded und are showing very often a greenish colorization. “Water-level-agates” are common for this locality.Mossy-like-structures in chalcedony are not rare.
more informations about the locality under www.canadianrockhound.com and at www.whitesailopal.com