The Goldpan Shamrock showing is located 6.9 kilometres southwest of Spences Bridge, at an elevation of approximately 300 metres. The showing largely follows close to the banks of the Thompson River in Goldpan Park.
Regionally, the northwest-southeast–trending Cretaceous Spences Bridge Group is part of the Southern Intermontane Tectonic Belt of the Canadian Cordillera, and is subdivided into the Pimainus and Spius Creek formations. The Spences Bridge Group volcanics are faulted against older plutonic and related metamorphic rocks of the Triassic-Jurassic Mount Lytton Complex. The dominant rock types within the area are subaerial andesite flows and tuffs, overlain by amygdule-rich basaltic flows. Minor felsic flows occur within these intermediate and mafic rocks, along with some sandstone, shale and conglomerate units. Stratigraphy is intruded by abundant Late Triassic and/or Jurassic to Miocene plutons. Metamorphic assemblages consist of Cache Creek Complex mélanges and Bridge River Complex metamorphic and ultramafic rocks. Quaternary sediments occur as thick drifts along the main rivers and some of the larger creeks.
Locally, the Spences Bridge Group is composed mainly of an accumulation of lavas and pyroclastic rocks that show great differences in lithology over short distances. Interbedded with these and occurring locally at the base, are minor amounts of waterlain material, consisting of tuffaceous conglomerates, sandstone, and waterlain tuff. These interbeds are minor components of the group in comparison to the volume of volcanic rocks. These volcanics are mainly andesite and dacite, but rhyolites and basalts are common. Breccias and agglomerates of both explosive and flow types form a large part of the group. Most of the lavas are porphyritic, fine- to coarse-grained rocks of various colors: red, green, mauve, purple, brown, grey, white and black. The agglomerates and breccias are mainly grey to green and contain clast fragments from 1 to 5 centimetres. Structurally, the Spences Bridge Group is generally gently folded, with dips from 10 to 40 degrees (Assessment Report 28521).
Mineralization has only been briefly described from rock samples near the site. Quartz occurs in various textures with vuggy quartz breccia, veins with limonite, banded quartz carbonate and chalcedonic quartz. Bleached volcanics were common but not described in detail.
Two grab samples of malachite-bearing quartz veinlets and stringers taken from the west side of the Thompson River in 2006 were found to be anomalous in copper. Sample 73282 contained 2619 parts per million copper and sample 73382, located approximately 700 metres to the south, assayed 2222 parts per million copper (Assessment Report 28521). An andesite float sample (73266) from the west side of the river was also anomalous, with 316 parts per million copper (Assessment Report 28521). Two of the drainages on the east side of the Thompson River were slightly anomalous in gold, assaying 25 (73251) and 30 (73257) parts per billion.
From 2005 to 2006, 665777 British Columbia Limited collected a total of 24 silt and 47 rock samples. Tanqueray Resources Limited then completed a program of property wide silt sampling, road soil sampling, rock sampling and follow-up grid soil sampling in the summer of 2006.
