Why Do Some Beaches Have Black Sand?

Ever wondered why some beaches have black beach sand and others don’t? Some black sand comes from volcanic activity near the coastline. When hot lava mixes with cold seawater, the lava will become hard and shatter into tiny little pieces. The other type of black beach sand is found near placers of minerals or precious gems.

Some beaches have black sand because there is basalt in the sand. Basalt is formed when hot lava makes contact with cold seawater. The sudden temperature change will cause the lava to shatter into millions of tiny pieces that look like black beach sand.

Let’s look at why some beaches have black sand and how common beaches with black sand are. Keep reading if you would like to find out if black beach sand is magnetic and what commercial uses for black beach sand.

Why Is Some Sand Black On The Beach

Black beach sand is caused by one of two natural occurrences. The one type of black sand we find on beaches is a glossy, heavy type of sand with some magnetic qualities because it contains the mineral magnetite. This is the most common naturally occuring type of black beach sand.

This magnetite-rich type of black beach sand is found near placer formations. Miners and prospectors can track magnetite-rich black sand to find placer formations. Precious metals and gemstones like Ruby, Topaz, and Sapphire are found in placer formations.

The other type of black sand we find on beaches gets its black color from basalt present in the sand. This basalt comes from volcanic deposits. When lava makes contact with water, the lava will cool down rapidly and shatter into the debris of various sizes.

Much of this debris will be small enough to be considered sand. A large enough quantity of lava flowing into the ocean can create enough basalt to turn a beach black overnight. This type of black beach sand can be temporary as the deposits are not replenished by the tides but rather volcanic eruptions.

Large waves can sort out the sand on sandbanks as the basalt has a different buoyancy than proper beach sand. The movement of waves will bring the heavy mineral basalt to the top and make the sand appear black to the naked eye.

Are Black Sand Beaches Common

There are about 20 black sand beaches in the world known to us. Compared to the 682 white beaches known to us, it is not that common. The rarity of black beaches results from the specific conditions under which black beach sand is formed.

Black beaches have become famous tourist destinations as the contrast of blue water, and black beach sand makes for very Instagramable holiday pictures. Because of the perceived rarity of black beach sand, it is, in fact, illegal to remove black beach sand in some places.

What Does It Mean If The Sand Is Black

If beach sand is black, it means one of two things. Either there is a viable placer formation in the area that can be mined for gems or minerals, or this beach has had a volcanic eruption in recent years.

Black sand does not mean that the beach is dirty. On the contrary, black sand is temporary to some degree, so you will most likely find black sand on a beach that has been left relatively untouched by the modern traveler. Fewer people means less rubbish and pollution.

From a beachgoers perspective, something to consider when visiting a black beach would be the temperature of black sand. Black sand is much hotter than white sand. Be sure to take appropriate footwear along. Black sand can get hot enough to blister human skin on contact.

Some native tribes in Hawaii and Australia consider black beaches as auspicious or holy. Ceremonies and celebrations are often held on these beautiful black beaches.

Why Do Some Beaches Have Black Sand 01

What Is Black Sand Called

Black sand is also referred to as Basalt fragments. Though basalt is not the only reason for black sand, it is the most common. Basalt is the name of the tiny fragments of volcanic rock present in domestic black beach sand.

Is Black Beach Sand Magnetic?

Black beach sand is indeed magnetic. The type of iron oxide that naturally occurs in volcanic deposits and heavy metal deposits is called magnetite. How magnetic the black beach sand depends on how much magnetite is present in the sand.

Next time you visit a black beach, bring along a strong rare earth magnet and try to test the sands magnetism yourself. The black beach sand should react to the magnet in the same way as iron fillings would.

Are Black Sand Beaches Man-Made?

Black beach sand is a natural occurrence. Black beaches are found naturally all around the globe, most notably in Spain, Hawaii, St. Lucia, Georgia, the Philippines, Puerto Rico, California, Martinique, Greece, the Caribbean, and New Zealand.

What Is Black Beach Sand Used For?

The Iron and Steel industry uses black beach sand to extract many types of ore used in construction.

Black beach sand also acts as a marker for mineral placer formations. The mining industry uses tracking techniques to establish whether or not they can viably mine minerals and precious gems in the area by analyzing the black sand deposits present.

Black beaches can be a useful resource for the tourism industry as it is relatively uncommon, and holiday destinations are marketed specifically for curiosity around black beach sand. Having a black beach in your country can attract plenty of foreign currency for the region.


Black beach sand occurs naturally in many places around the world. Black beach sand is formed when lava meets seawater. The drastic temperature change will cause the lava to fracture into tiny pieces called basalt. The basalt deposit on the beach will make the beach sand appear black.

Black beach sand is a valuable resource as the Iron and Metal industry uses it for ore extraction, the mining industry as markers for mineral placers. Black beaches are very popular holiday destinations because of black beach sand’s aesthetics and perceived rarity.