The mine is also the type locality for the phosphates englishite, gordonite, millisite, montgomeryite, overite and wardite.
These were undoubtedly gordonite crystals, some up to a quarter inch long and of excellent transparent quality.
On October 27, 1937, he wrote as follows to his friend Sam Gordon (namesake of gordonite) at the Academy of Natural Sciences in Philadelphia (quoted by Conklin, 2002):
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).
It occurs in cavities with wardite, replacing both wardite and variscite, and resembles gordonite, but is more platy, and the cleavage surfaces tend to be larger and curved.
Summing up their work on Sapucaia phosphates, Lindberg and Pecora (1958) listed their apatite, bermanite, childrenite, gordonite, heterosite, hureaulite, leucophosphite, lipscombite, metastrengite (= phosphosiderite), montebrasite, roscherite, saleeite, strengite, triphylite, variscite and vivianite as having been positively identified, in addition to the new species.
The silicate assemblage consists of altered albite as a host for apatite, hureaulite, goethite, gordonite, leucophosphite, phosphosiderite, rockbridgeite, saleeite, tourmaline and variscite; altered beryl as host for faheyite, moraesite, roscherite and variscite, and muscovite hosting replacements and vug fillings of apatite, bermanite, childrenite, faheyite, frondelite, montebrasite, roscherite and variscite.
Gordonite Mg[Al.sub.2][(P[O.sub.4]).sub.2][(OH).sub.2][multiplied by] 8 [H.sub.2]O
Gordonite occurs in colorless vitreous crystals, usually tabular, in some cases diamond-shaped, and as crusts with leucophosphite, saleeite and fluorapatite in albite vugs.