| Sand
FAQ
What actually is sand?
Sand is a granular material made up of fine loose particles
ranging in size from 0.0625 mm up to 2.00 mm. Particles larger
than 2.00 mm are referred to as gravel, while particles
smaller than 0.0625 mm are referred to as clay. Sand is
commonly divided into five sub-categories based on size:
- Very fine sand - 0.0625 to 0.125 mm
- Fine sand - 0.125 to 0.25 mm
- Medium sand - 0.25 mm to 0.5 mm
- Coarse sand - 0.50 mm to 1.00 mm
- Very coarse sand - 1.00 mm to 2.00 mm
What are the different sand
categories?
There are three main types of sand - mineral sands, biogenic
sands and precipitated sands. Mineral sands form from the
mechanical and chemical breakdown of rocks. Biogenic sands,
also known as carbonate sands, are formed from the remains of living
organisms such as corals, forams, shells, gastropods, tube
worms and so on. The third category, precipitated sands, are
formed by a chemical process whereby minerals are precipitated
out of an aqueous solution, such
as in shallow lakes or the sea.
What kind of materials is sand comprised of?
Sand is generally made up of a mixture of different
materials with the most common being minerals such as quartz
resulting from the break down of rocks. Some sands may be
comprised of organic remains such as shell and coral
fragments or the skeletal remains of marine organisms such
as plankton. The composition is very much dependant on the
nature of local materials. For example, sands in
volcanically active regions may consists of ash or other
related fragments and the sands around coral atolls might
consist entirely of coral fragments. How does sand
accumulate, for example, on beaches?
Sand accumulates by a variety of processes with perhaps the
most well known being the action of waves and currents in
coastal areas - most of the sand on beaches accumulates this
way. Another well-known process that brings sands together
is the wind and examples would be sand dunes found along the
coast and in desert areas. The process of erosion by
rivers, and even glaciers, also causes sand to accumulate. What
kind of minerals can I find in sand?
There are many different minerals found in sand including
quartz, feldspar, mica, calcite, gypsum, hornblende, zircon
and many others. As well as minerals sand may also contain
rocks fragments such as basalt, magnetite, pumice or
precious material such as garnet, amethyst or even gold! Why
do the sands on different beaches vary in colour?
The colour of any sand is down to the different minerals or
mixture of minerals and other particles that makes up the
sand. For example, white sands can often consist entirely of
the white remains of corals or limestone. Black sands may be
made up of dark coloured volcanic materials such as
magnetite, which can be picked up with a magnet or even particles
of marine coals exposed along the shore. The mineral olivine
is responsible for some green sands and reddish or cream
coloured sands are often comprised from particles of eroded
sandstone. |
