Secondary phosphates found in the Stewart pegmatite include hureaulite, sicklerite, purpurite, heterosite, stewartite, and phosphosiderite.
Along with gem spodumene and tourmaline, Jahns and Wright (1951) list quartz, perthitic microdine, albite, beryl (morganite and aquamarine), bavenite, bertrandite, numerous bismuth-containing minerals including native bismuth, bismuthialte, bismutite, and bismite, and nurnerous phosphates including lithiophilite, triphylite, sickletite, purpurite, heterosite, stewartite, and hureaulite.
The alteration of triphylite results in the formation of heterosite and many other phosphate minerals, arranged in a crude zoning around the triphylite masses.
Large phosphate pebbles and boulders are often exposed in the creek bed after heavy rains; these are generally massive triphylite or frondelite, with or without alteration minerals, or heterosite sometimes showing good crystals.
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.
During the summer of 1982 a forest fire uncovered old phosphate stockpiles near the access road close to the ford (fine frondelite and heterosite and excellent phosphosiderite).
Vein deposition of montebrasite, pyrite, quartz, sphalerite, tourmaline and zircon coexists with replacements of triphylite (usually along cleavages) by heterosite, barbosalite, frondelite, jahnsite, phosphosiderite, rockbridgeite, tavorite and manganese oxides.
The frondelite assemblage consists of residual heterosite, [TABULAR DATA FOR TABLE 1 OMITTED] montebrasite and triphylite enclosed by frondelite; massive replacement of frondelite by cyrilovite, cryptomelane and leucophosphite; and fracture coatings in frondelite of bermanite, cyrilovite, goethite, leucophosphite, lipscombite, mitridatite, moraesite, opal, phosphosiderite, rockbridgeite, variscite and manganese oxides.
Sapucaia is the type locality for barbosalite, where it occurs mainly as a very fine-grained, dark blue-green layer at the boundary between heterosite and porous triphylite.
Cavities near heterosite contain the most barbosalite.