DECOMPOSED GRANITE |
The quarry is situated in the
Randfontein District, on the R 500 between Carletonville and Randfontein. We
are fortunate that the farm on which we are situated and its surroundings has a
good supply of Decomposed Granite.
Decomposed Granite, also known as
DG, is granitic rock that has weathered to the point that it readily fractures
into smaller pieces or chunks of weak rock. Further weathering produces rock
that easily crumbles into mixtures of gravel, sand, and silt-sized particles
with some clay.
Granite is composed of
plagioclase feldspar, orthoclase feldspar, quartz, mica and possibly other
minerals. The chemical transformation of Feldspar, one of the primary
constituents of granite, into the clay mineral kaolin is one of the important
weathering processes. The presence of clay allows water to seep in an further weaken
the parent rock allowing it to fracture or crumble into smaller particles.
Grains of silica in the granite are relatively resistant to weathering and may
remain almost unaltered.
|
|