What is sand, and what is its chemical composition?

Natural sand is a loose sedimentary rock that has formed over millions of years through weathering.

Wind, rain, snow, water flowing down mountains, sun, frost, and movements of the earth’s crust erode mountains. Small cracks turn into large cracks that make the stone fragile, pieces fall off it and crumble further until they become tiny grains – grains of sand – ranging in diameter from 0.16 mm to 5 mm.

Wind and water carry the grains of sand, gathering them together, gradually forming large loose clusters – sands. The grains of sand are so small that there are about 2,000,000,000 of them in 1 cubic meter!

Rocks are the primary sources of sand

Geologists determined that the progenitors of the sand are massive rocks like sandstone, gneiss, and granite. When weathered, their individual elements disperse, dissolve, and only the strongest ones remain, mainly quartz, or silicon oxide. It is one of the most stable compounds on the Earth’s surface and makes up the base of the sands, 99.9% of their total volume on the Earth.

Sands contain feldspar, mica, and other minerals in much smaller amounts. In some sand clusters, you can find tiny shells of mollusks, and fossilized remains of animals and plants that existed millions of years ago. The shells comprise calcium carbonate, the familiar chalk.

Types of natural sand

According to the conditions of accumulation.

Depending on how the grains of sand accumulated into huge masses, sands are divided into:

alluvial – deposits formed by the constant flow of rivers and streams;

deluvial – deposits at the foot of elevations (rocks, mountains, hills);

lacustrine – lenticular deposits at the bottom of lakes;

aeolian – sediments brought by the wind;


By color

The shade of sand depends on its composition. For example, the sand at Pfeiffer Beach in California (USA) has a purple, even lilac hue because the local sand quartz has a lot of the mineral spessartine containing lead and manganese. Refracting in the microscopic particles of spessartine, the sun’s rays create a visual “purple illusion”.

The name of the Kyzyl-Kum desert is translated as “red sands”. The sand there is really red, bright red, or reddish-red in some places. It is caused by the destruction of red-soil soils, which colored the sand clusters destroying them.

But the KaraKuma desert is “black sands” (literal translation). However, the grains of sand are not black, but dark gray. The reason is the relative youth of the sands, which have not undergone repeated bleaching and bleaching. A rich mineral composition: there are 42 types of minerals in the Kara-Kum Sands! Among them, there are tourmalines, garnets, mica, quartz, and greenish and pink grains of feldspar.

The sand at Punaluu Beach in Hawaii is truly black. The color is given by the basalt crumbs, which are transformed into lava that once flowed out of the nearby volcanoes. The shade of the beach is so strong that the place is declared a protected area and even a handful of sand from it can not be taken out. The composition of black sands, which are found in other regions of the Earth, has over 50 kinds of minerals. The major components are magnetite, ilmenite, and hematite.

The fantastically white sand is on Hyams Beach, 300 km from Sydney, in Jarvis Bay. It is so white that it is even listed in the Guinness Book of World Records. It looks like the tiniest bit of salt or snow has been scattered along the shore. Like snow, this sand is dangerous to the eyes – it dazzles. That’s why everyone on the beach only wears sunglasses. Scientists have not yet discovered the snow-white sand – the composition of its grains is the most common.

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