When choosing a summer holiday destination we often find ourselves looking at different beaches. Some of you might have noticed that they come in a variety of colours. And it doesn’t depend on their geographical location. Look at Greece. There are plenty of beautiful, white or yellow sand on the shore of Greek islands, but you can find black beaches there too! Why is this so?
It all starts with the process of sand formation. It is made from rock and minerals, which are subject to destruction through mechanical or chemical erosion, abrasion and extreme changes of temperatures. All these processes break down rocks into smaller fragments, which are transported via wind and water (e.g. rivers, rainfall) towards the sea. The most common types of rock are made up of silica and calcium carbonate.
All the sand in the world is made in the same way. So why can it be so different? It’s because there are various kinds of minerals that contribute to the formation of rock. So different minerals found in given areas affect the colour of the sand.
Let’s look at the standard, yellow-coloured beaches, which can be found in Southern Europe. Their sand is formed of quartz, which contains traces of iron that give the yellow colour. Quartz without those impurities forms white sand. This is common in beaches in tropical regions such as Cape Santa Maria in the Bahamas or those beaches found on Caribbean Islands. This colour is also the result of mollusk shells and corals, whose white colour contributes to the clear white colour of the beach.
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However, beaches can look a bit more extraordinary. Those located near volcanic deposits can display a variety of colours, mainly black, which is caused by the presence of basalt. Basalt is a rock which forms when water meets hot lava. It then cools down and breaks into small pieces. One of those beaches can be found in Iceland and was once placed in the top ten most beautiful beaches in the world. Black sand is also the results of placer deposit formation, which is an accumulation of the various minerals found at the bottoms of rivers and lakes. They can contain more valuable minerals such as sapphire, gold or even diamonds.
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Some very strange beaches can be found in Hawaii. Apart from the volcanic ones, red or even green sand can be found there. The former is caused by the excess of iron and is present at the Maui island, the latter by the the mineral olivine near Papakolea Beach. California boast purple beaches, for example Pfeiffer beach. Its colour is caused by another manganese garnet from the surrounding area.
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One of the most mesmerizing beaches in the world is a pink beach found in Bahamas. Similarly coloured sand can be found elsewhere, typically near coral reefs. One of the organisms living in the reef is red and when it dies it falls to the bottom of the ocean. The waves move it to the shore and its small particles mix with the sand resulting in beautiful light pink shade of the sand.
If all those minerals have such an impact on the colour of the sand there must a place where there is more than one odd colour present. Rocks where the minerals are mixed, such as those formed in an Ice Age can produce multiple different coloration of the beach. That is the case at The Rainbow Beach in Fraser Island in Australia, where one can see even 70 colours displayed on the sand.