The mine is also the type locality for the phosphates englishite, gordonite, millisite, montgomeryite, overite and wardite.
Larsen (1942b) made a detailed study of the paragenetic relationships in the evolution of variscite nodules in the Clay Canyon deposit, identifying six stages: (1) variscite formation, followed by fracturing and the introduction of thin black quartz veinlets; (2) banded minerals, primarily crandallite, millisite and wardite, replacing and enclosing variscite while opening up cavities through shrinkage (some variscite nodules were entirely replaced by crandallite); (3) formation of free-growing crystals of gordonite, englishite, montgomeryite and probably overite and kolbeckite in cavities; (4) a minor reversion to crandallite formation from solution as isolated oolites; (5) apatite-group minerals; and finally (6) the limonitic phase (limonite is not present inside any of the nodules).
Englishite generally occurs in association with montgomeryite and is the earlier-formed of the two.
Montgomeryite was named after Arthur Montgomery by Larsen (1940) based on crystals from variscite nodules collected by Montgomery and Over at Clay Canyon in 1936 and 1937.
This year his stock included remarkable acicular warwickite microcrystals from the La Cella mine near Jumilla, Murcia Province; microcrystals of montgomeryite
and alumohydrocalcite from Montcada in Barcelona Province, melilite and nepheline from a basalt quarry near Ciudad Real, and microcrystals of synchysite-(Ce) from the Valle de Aran in Lerida Province.