The Criterion-Oyster claim group is part of the Meridian property (082KNW064) and adjoins the Eva (082KNW066) on the southeast. In addition to a number of surface cuts on these claims, a total of 780 metres of underground development work has been done mostly on two levels following the Criterion vein. This vein is sub-parallel and appears to converge with the 'A' vein of the Eva mine. The ore was transported from the mine to the mill by a 1066- metre-long aerial tram; the mill at Camborne was operated by water power taken from Pool Creek below the intake of the Eva flume.

The Criterion vein is a well defined and persistent structure that strikes 120 degrees and dips 70 degrees northeast. No. 1 level develops the vein 30 metres below its surface outcrop following a continuous ore-shoot 300 metres long, averaging 1.5 metres wide, from which about 12,700 tonnes of ore was extracted. The vein is partly the result of fissure filling with quartz and replacement of the brecciated country rock consisting of carbonaceous phyllite. In places the vein is solid quartz but elsewhere it is comprised of a mass of reticulating quartz veinlets with phyllite between. It has been suggested that the carbon in the phyllite has acted as a precipitating agent for the gold contained in the mineral-bearing solutions - the highest grade of gold occurring around the carbonaceous inclusions. Underlying rocks are assigned to the Broadview Formation of the Lower Paleozoic Lardeau Group

The Criterion vein is cut by a mineralized fault striking 043 degrees known as the 'galena vein'. Where it cuts the Criteron it narrows from more than 1 to 0.3 metre wide, retaining well defined gouge seams along slickensided walls. This younger vein has been explored for 106 metres by drifting on the No. 1 level to a point where it is finally cut off by a shallow south-dipping east-west fault. At 160 metres in the tunnel another quartz vein, 2.4 metres wide - similar to the 'A' vein at Eva, was encountered. The No. 2 tunnel, 53 metres below the upper level, was driven 137 metres to intersect the Criterion vein, however, the continuation of the ore- shoot, mined out on the No. 1 level, was not encountered.

The Oyster vein outcrops 90 metres north of the Criterion. It strikes 145 degrees, dips 65 degrees northeast and extends onto the Lucky Jack (082KNW187) property to the southeast. The only development on the vein is a series of trenches.

See Meridian for 1904 production (Great Northern Mines Ltd.) record (9164 tonnes, resulting in 50,169 grams of gold and 18,662 grams of silver).