Howdy,
The Grants District is split almost 50/50 between Cibola & McKinley Counties, NM. The Poison Canyon Area is, however, entirely in McKinley County. Cibola Co is a relatively new political designation created in 1981 from the West 3/4s of Valencia Co. This was the source of the confusion some years ago concerning the East Grants Ridge topaz & spessertine location now in Cibola Co. (I think this has been fixed in Mindat - I haven't checked).
At any rate, any reference to the Poison Canyon Area should be changed to McKinley County, NM.
See: Rautman, C.A., "Geology and Mineral Technology of the Grants uranium region 1979", Memoir 38, New Mexico Bureau of Mines & Mineral Resources, 1980, 226-229, map p19.
Also, Northrop/LaBruzza, "Minerals of New Mexico, third eidtion", 286.
Thanks
Don