In technical terms, sand is a granular material, with a size slightly larger than silt but smaller than gravel.
The characteristics of sand can vary greatly depending on its formation location. It can be fine or coarse, and it comes in colors such as white, black, yellow, green, orange, or red.
Based on the properties of sand, experts can explore the geographical area where it was formed.
The most common type of sand on Earth is primarily composed of silica, typically existing in the form of quartz, originating from the Earth’s crust. This transformation occurs over millions of years through the weathering processes of the Earth’s crust. Additionally, continuous flows erode rocks, breaking them down into sand grains.
Beach sand is formed from quartz and feldspar, due to weathering and erosion of mountains.
Sand can also be made up of coral fragments, animal shells, or even the remains of fossilized organisms such as foraminifera, sponges, and mollusks…
White sand formed from coral fragments containing calcium carbonate.
Sand grains flow along rivers into the sea, a process of sediment deposition that can take hundreds of thousands of years. Furthermore, each type of sand has a different color.
- The most commonly seen is brown sand, such as at Vung Tau beach in Vietnam, which originates from quartz and iron oxide in feldspar.
- The black sand beach Punaluu in Hawaii, USA, is formed from volcanic basalt lava.
- The green sand beach Papakolea in Hawaii, USA, is made from green minerals known as olivine.
- White sand beaches are formed from coral fragments containing calcium carbonate.
Upon thorough analysis, different sand beaches reveal varying compositions, resulting in the diversity of sands around the world.
About 1/10 of sediments drifting into the sea consist of sand. These grains range in size from half a millimeter to 2 millimeters – roughly the thickness of a coin. They are large enough not to be swept away into the deep ocean.
However, beaches are merely temporary stops for sand. Large waves will carry it away from the shore, while smaller waves will push it along the coastline. Therefore, to maintain the beautiful brown color of the sand on the beach, it is crucial to ensure a constant supply of sand.
Yet today, many beaches are facing a sand shortage. Dams blocking rivers have prevented sand from reaching these areas, accumulating in reservoirs. Human activities have caused the amount of sand that would normally be transported to beaches worldwide to be reduced by up to half!
Humans cannot stop the waves from crashing. Consequently, beach sand continues to be washed away without replenishment, leading to gradual coastal erosion. This means that many beaches around the world are slowly shrinking, inevitably.
Currently, sand is the third most exploited natural resource in the world, after air and water.
