Described as a columbate and tantalate of Ti, U and Fe, from Divinésia (ex-Divino de Ubá), Minas Gerais, Southeast Region, Brazil. The name was given by Gagarin and Cuomo to material described by Guimaraes in 1926. (see Dana's 7th, Vol. I, p. 807.)
References for Guimaraesite (of Gagarin & Cuomo)
Reference List:
Am. Min. 36,638-642 (1951)
Min.Mag. 29, 983 (1952)
Internet Links for Guimaraesite (of Gagarin & Cuomo)
(TL) indicates type locality. ? indicates mineral may be doubtful at this locality. All other localities listed without reference should be considered as uncertain and unproven until references can be found.