The Yellow Lake feldspar showing is located in a steep gully, immediately northwest of Yellow Lake and Highway 3A between Keremeos and Penticton, British Columbia.

Phonolite lava flows of the Eocene Yellow Lake Member of the Marron Formation, Penticton Group outcrop near Yellow Lake, west of Okanagan Falls. The rock consists of fine grained, pyroxene-rich mafic lava with locally well developed plagioclase and aegirine-augite phenocrysts.

Twelve samples collected from different outcrops were analysed to evaluate whether the rock is a potential source of feldspar for industrial applications. Results are as follows:

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Major Oxides Weight Per Cent

SiO2 50.07 - 64.67

Al2O3 13.63 - 19.49

Fe2O3 3.30 - 6.93

CaO 1.46 - 8.47

Na2O 3.05 - 5.86

K2O 4.42 - 6.97

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All samples tested contain high amounts of iron. The sample with the least iron was sent to CANMET for processing to determine whether impurities could be reduced to industry standards but the rock was considered to be too fine grained for mineral separation studies and cannot meet the specification for amber glass (Fieldwork 1988, page 487).