The Amethyst showing is underlain by a sequence of volcanic and sedimentary rocks of the Lower Jurassic Telkwa Formation of the Hazelton Group. Host rocks consist of thick-bedded purple to green lapilli tuffs and volcanic breccias dip steeply northwest and are commonly cross-cut by intermediate dikes. Black mudstone and siltstone occur in the vicinity.

The Amethyst Showing consists of a several metre wide shear zone exposed in a major north to northwest trending creek. The zone consists of well sheared, pyritic volcanics with abundant quartz stringers and silicification. Lenses of amethyst occur at the southern end of the showing; carbonate alteration is also common. Very minor amounts of galena are associated with the amethyst lenses. The zone is traceable along strike for about 70 metres and is immediately overlain by a coarse grained quartz-feldspar porphyry dike. Five samples were taken from the zone. Gold values are only slightly above background in one sample (the only one which contained amethyst). Silver values are 17.8 parts per million in this sample, however, and anomalous arsenic, antimony, bismuth, selenium and tellurium were detected in this and other samples making the zone of interest (Assessment Report 16677).

See Main Creek (Coles) (093E 110) for related details. The Amethyst showing is about 1 kilometre west or the previously defined Coles vein system, a 4 kilometres long northwest trending system that originally included showings from Camp View, to the northeast, to the East Side and South Side showings at the southeast.