The NAZKO PERLITE occurrence is located on the Nazko Plateau, approximately 28 kilometres east of the village of Nazko and 47 kilometres west of Quesnel. Perlite was found, in 1994, during a cursory examination of large rhyolite outcrops and an adjacent bank of glacial outwash exposed in a cut on the road from Quesnel to Nazko.

The area is underlain by grey, purple and buff-coloured, fine-grained dacitic to rhyolitic tuffs of the Ootsa Lake Group in fault contact with a window of Triassic Hazelton Group sediments and volcanics.

While no bedrock outcrops containing volcanic glass are known in the area, abundant clasts of perlitic rock can be found throughout the outwash deposit. The large size of many of the perlite boulders (50 centimetres in diameter), low physical strength of the rock and proximity to a large exposure of Eocene rhyolites (Rouse and Mathews, 1988; Tipper, 1961), points to a nearby source, most probably associated with the adjacent rhyolite outcrops.

XRF geochemical tests conducted in 2019 on four rock samples showed the glassy perlitic volcanics to have very low calcium levels (0.848 to 1.17 per cent CaO), with aluminum ranging from 3.89 to 4.65 per cent Al. Silica content was very high, ranging from 16.75 to 21.50 per cent Si (Assessment Report 38788).

The perlite rock is black to dark green, with microfractures resulting in platy, rod-like and isometric fragments. Four distinct types of volcanic glass were collected for expansion tests. A sample of each of the four types was crushed to less than 1-centimetre size fragments, which were then placed under a propane torch flame for about 1 minute. All types expanded, increasing the volume of individual particles from approximately two to four times their original size. Tests conducted in 2019 indicated expansion to be at least five times the original volume.

The significance of this perlite occurrence is that it is the logistically best-located and accessible site in the British Columbia interior, and the authors (Hora and Hancock) believe that prospecting will locate the bedrock source of perlite rock in nearby Eocene rocks. According to Peter Read (personal information, 1997) the bedrock source has been found nearby.