Unveiling the Mystery: What Gives Sand Its Colour

Underneath our feet lies a mysterious world – sand – a tapestry of grains woven with different hues. From the serene tropical beaches to the dune-covered desert, nature has carefully curated sand with dozens of shades, mirroring the diverse landscapes it hails from.

Amid all these, comes the million-dollar question: What gives the sand its colour?

In this fin-tastic article, we will dig deeper to throw different formations of sand that give it different colours.

Contents show

What is Sand?

Sand is a granular material made of coarsely divided minerals and rocks. As rocks weather away, erode, and crumble over vast periods – thousands, and even millions of years – they turn into what we call sand – a funky granular concoction.

Sand particles can be of different sizes – from 0.0625 to 2 millimetres in diameter – each giving sand the mysterious texture to blow you away!

Quartz is the ultimate material in sand. However, the landscape sand belongs to and the composition of the rock sources play critical roles in determining its makeup. Quartz is a compound of silicon – silica (SiO2.@

The formation of sand is a tale of perseverance that describes how these groovy particles give different textures, colour, and shapes to the Earth’s surface encompassing the dune desert, rugged coastline, and seafloor.

What Gives Sand its Colour?

The catalysts behind the mesmerising hues of sand are the minerals the sand-formating rocks preserve in them. Each hue tells a unique story carefully composed by the mineralogy, location, and environmental factors acting upon the sand in concern.

The most common minerals found in the quartz in the sand are iron dioxide, feldspar, olivine sandstone, etc.

On the other hand, geological processes such as sedimentation, erosion, and weathering play a critical role in the allocation and composition of these minerals in sand. For example, mineral-rich rocks and gravel, when undergoing erosion, cause these minerals to leach into water. Later, these minerals are transported to the coastal areas by wind, waves, and glaciers, influencing the hue of coastal sand. For beach sand, minerals from the bodies of different sea creatures such as coral reefs, can also accumulate in the seawater, thereby transporting to the sand.

Climate condition also plays a critical role in sand composition, thereby, passively impacting the colouration process. For example, In dry regions where rainfall is scarce and temperature remains high, physical weathering such as thermal stress and abrasion, is more prevalent. Minerals in these areas, when broken down, create more coarse and angular sand particles that are often of light hues. In humid climates, where water and moisture are abundant, rock minerals are more susceptible to chemical weathering processes that form sand of a range of colours – from light to darker shades.

The interplay of minerals of different shapes, textures, and composition, geological processes, and environmental factors such as airflow, water, sunlight, etc., further influence the oxidation and coloration of minerals in sand.

Most Common Colours of Sand

Figure: different sands around the world

White Sand

As we know, sand is made of quartz – a white compound of silicon and oxygen. If there are impurities in quartz, the sand looks a little yellowish. Quartz with no impurities is called white sand.

And voilà! If you want to enter the realm of radiant white sand wonderland, look nowhere other than Hyams Beach in New South Wales, Australia. The primary ingredient of this beach sand is finely ground pure quartz crystals. Besides quartz, white sand can be made of coral, shell fragments, etc. For example, the ingredient of the renowned white sand beaches of Hawaii is finely ground calcium carbonate sources from the poop of parrotfish.

Yellow Sand

Quartz grains with iron-oxide coating on them can cause sand to look yellowish. An example can be the sand in the Namib Desert – a dune land with golden-yellow tones mainly due to the rock grains being rich in iron.

Brown Sand Beaches

When sand of a particular landscape has an increased amount of iron oxide concentrated in it, it looks brownish instead of yellow. The degree of weathering, erosion, and presence of minerals, etc., also play a critical role in determining whether the sand will look yellowish or brownish. An example of brown beach sand is Rockaway Beach in Pacifica California.

Its chocolate-coloured sand looks tempting to stuff your face with but hold your horses. Well, go on if you love the taste of volcanic greenstone and limestone, because this is where this tempting chocolate colour comes from! While the chocolate colour might tempt you to take a bite of this peculiar-looking sand, I wouldn’t recommend it, unless you love the taste of limestone and volcanic greenstone – the ingredients of the sand there.

Red Sand

Places like Red Sand Beach in Maui, Hawaii, and the Outback deserts of Australia sport red sand – a quartz composition that has iron oxide and other iron-rich minerals, such as hematite deposited on it. The process of colouring sand in red hue starts with the withering or erosion of these iron-based minerals from rocks present in a place.

Factors, such as wind, ice, or water play a critical role in transporting these minerals as rocks decay and break down over time. Throughout this process of transportation, iron content in the sediment gets increased further as the existing minerals react with other organic matter and minerals present in the land. These sediments settle down and look red.

Grey and Black Sand

Get ready to get mesmerised by the whimsical grey and black sand as they unveil the mystery of their enchanting composition and intrigue! Grey sand is found in the rugged Shelter Cove in Humboldt County, California, and various beaches on Santorini Island.

A blend of minerals, such as basalt, shell fragments, and volcanic ash, the grey hue of these places creates a landscape into a unique timeless environment. Just like grey sand, the main constituent of black sand is basalt. Volcanic basalt when blended with magnesium and other iron-rich minerals gives sand a deep-back hue.

This dark colour is a testament to ancient volcanic activity that has left its mark behind on the Earth’s surface, forming landscapes that symbolise breathtaking beauty and intrigue! The alluring beauty of black sand can be experienced in the Punalu’u Beach in Hawaii or Vik Beach in Iceland.

Pink Sand

Horseshoe Bay Beach in Bermuda, and Pink Sand Beach in the Bahamas are some of the majestic beaches where the enigmatic pink sand, with its whimsical hues of rosy elegance, are waiting to mesmerise you.

The pinkish glow in the sand of these beaches owes its charm to – foraminifera – a single-cell marine maestro having a mineral-made shell in its body. The constituent of these shells is predominantly calcium carbonate, and the hues range from gentle pink to fiery red.

When these organisms die, their shell remnants waft ashore. These foraminifera relics, by combining with coral and pure quartz grinds, craft the pink-toned sand.

From the golden desert of Namibia to the crystal white beach sand of Hyams Beach in Australia, the variation in colour of sand across the world reminds us of how carefully nature has curated the planet.