The 2-billion-year-old (Archean) Phalaborwa Carbonatite Complex contains apatite-bearing zones, the primary source of South African phosphate production. Phalaborwa carbonatite contains two types of apatite ores: foskorite and pyroxenite.
The manufacture of phosphoric acid from phosphate concentrate produced a phosphogypsum waste which has been deposited on 2 large stacks. The REE in the phosphate ore reports primarily to the phosphate concentrate delivered to the PA plants.
The two stacks are situated to the West of the Phalaborwa mining complex. The residue stacks were deposited on a relatively flat base, consisting of soil and gravel, which was intersected in some of the drill holes.
Stack A, the largest of the 2 stacks, with an approximate basal dimensions of 1,200 m x 700 m, has a higher surface elevation and steeper slopes. An acidic water pond (with a depth of c.4 m at its deepest central part) covers most of the top centre of the stack. Some gypsum has been mined for agriculture purposes has been removed from the NE corner of stack A.
Stack B, with an approximate basal surface of 800 m x 650 m, is lower and has gentler slopes than stack A. The acid pond on top is smaller, but with a depth virtually the same as for stack A. Some gypsum quarrying and mining has taken place in the SE and SW corners of stack B.
In both stacks, the material is made of white, fine-grained, friable phosphogypsum which is indurated/ceme ........
