How is black sand formed in Hawaii?


Sand is the result of a variety of processes, including the breakdown of organic wastes like parrotfish excrement and pebbles.

Sand is found in a variety of places, sources, and habitats. It is created as rocks erode and weather over decades or even millions of years. The decomposition of rocks, particularly quartz (silica) and feldspar require time.

Rocks slowly move down rivers and streams, often beginning thousands of kilometers from the ocean, continually disintegrating along the way. When they reach the ocean, the repeated wave and tide action cause them to degrade even more.

Iron oxide, which gives quartz a light brown color, and feldspar, which is brown to tan in its natural state, combine to give most sand beaches their tan color.

The production of sandy beaches is also significantly influenced by the by-products of living creatures. Bermuda’s abundance of delightfully pink beaches is the product of foraminifera, single-celled, shelled creatures that continually decompose.

Less common but no fewer appealing beaches that rely on an altogether other ecological processes instead of quartz as a supply of sand. For instance, the famed white sand beaches of Hawaii were really formed from parrotfish waste. The fish’s parrot-like beaks are used to bite and scrape algae off rocks and dead corals. Their intestines then ground up the inedible calcium-carbonate reef debris, which is primarily composed of coral skeletons, and expel it as sand. Parrotfish may generate hundreds of pounds of white sand a year, all while contributing to the preservation of a rich coral-reef habitat.

Black Sand

From the name itself, black sand is sand that is black in color. A placer deposit may contain black sand, which is a heavy, glossy, partially magnetic combination of typically fine grains containing minerals like magnetite.

Black sand is commonly found on beaches close to volcanic activity and is made from degraded volcanic debris including lava, basalt rocks, and other dark-colored rocks and minerals. Black-sand beaches are mostly seen in Hawaii, the Canary Islands, and the Aleutians.

Even while certain beaches are mostly formed of black sand, other beaches, such as those that are gold or white, can frequently contain deposits of the darker sand, especially after storms. Sand grains can be separated by larger waves, exposing deposits of heavy minerals on the surface of erosion escarpments.

Sand Composition

In Hawaii, beaches may be comprised of “white sand” produced by sea creatures, “black sand” created by the erosion of volcanic rocks, or a combination of the two. Black sand beaches, for instance, are quite prevalent on the windward side of the Big Island. Nearly all the South Point beach’s sand is green of olivine, a frequent mineral found in Hawaii’s volcanic rocks. The beaches on the Kona coast of the Big Island and the neighboring islands have a variety of mixed compositions, some predominating with calcareous (reef-derived) silt, and others with a significant volcanic (detrital) component. Seaside and the research region, Kailua Bay on windward Oahu, is nearly exclusively calcareous, reef-derived material in its subsurface sands. Only 5% of the sand grains on average contain volcanic materials orbits of rock. Each beach is distinctive and has its own supply of sediments.

The “white” beaches and marine sediments in Hawaii are primarily made up of carbonate shells and skeletons of marine organisms like corals, algae, mollusks, foraminifera, echinoderms, and bryozoans. This is because Hawaii does not have a continental source of quartz sand like beaches on the mainland do.

How is Black Sand Made?

Beaches with black sand can develop in a few distinct ways. One method involves the erosion of volcanic rock caused by water flowing down a volcano’s flank. The erosion brought on by rivers and streams can cut through the dark volcanic rock. The eroded rock fragments often continue to deteriorate as they move into the ocean, where the little sediments are subsequently discharged. When hot lava strikes cold ocean water and rapidly cools, it shatters and breaks into bits of basalt shards of all sizes, including grains of black sand. This is another prevalent method that black sand and black sand beaches are generated. A new black sand beach can grow overnight during a volcanic eruption because of the amount of lava that can interact in this way with the water.

Sand and lava rocks taken from any of the islands’ stunning beaches are prohibited in Hawaii. The best way to appreciate the stunning beaches is to unwind, sit back, and snap several photos while you are here. The fact that black sand is a finite resource and decomposes more quickly than other forms of sand is one of the reasons it is illegal to steal any rocks or sand. Due to the sand’s juvenile makeup, it is particularly susceptible to weathering and degrades quickly.

Do the Other Hawaiian Islands Have Black Sand Beaches?

There are many black sand beaches on the Big Island since there is a lot of volcanic activity there. Punalu’u Black Sand Beach is the most well-known black sand beach on the Big Island. Due to its rocky shoreline, this beach is not the finest for swimming, but it is a lovely spot to unwind and look for sea turtles such as the Hawksbill Turtle and Green Turtle.

On Hawaii’s Big Island, there is another black sand beach called Kehena Beach. It is close to Puna on the east side of the island. This beach is one of the few in Hawaii that permits nudity, so be mindful of that.

On the Big Island, Kaim Beach Park is situated at Kalapana. Before it was devastated by lava flows following a volcanic eruption in 1990, the bay was well-known across the world for its black sand beach, which was bordered by shade palm palms. It is currently one of the Big Island’s newest black sand beaches because of that eruption. The nearest Big Island black sand beach to Hilo is Richardson’s Beach. Because of the calm ocean and wonderful picnic space, this beach is an excellent spot to bring kids.

On the Big Island, Waipio Valley is home to Waipio Beach. Getting there might be difficult due to the road’s high incline. But the trek is worthwhile, especially for surfers.

20 Best Black Sand Beaches in the World

Considering spending time in a far-off locale on your upcoming vacation? Nothing compares to a beach with black sand. The greatest black sand beaches in the entire globe are:

1. Reynisfjara, Iceland

2. Diamond Beach, Iceland

3. Kaimu, Hawaii

4. Waianapanapa State Park, Hawaii

5. Stokksnes Beach, Iceland

6. Lovina Beach, Bali, Indonesia

7. Playa Negra, Costa Rica

8. Prince William Sound, Alaska

9. Playa Jardin, Spain

10. Miho-no-Matsubara, Japan

11. Panalu’u Beach, Hawaii

12. Marigot, Grenada

13. Soufriere, St. Lucia

14. Kamari Beach, Greece

15. Playa Negra, Puerto Rico

16. Papenoo Beach, Tahiti

17. Karekare Beach, New Zealand

18. Tangkoko Nature Reserve, Indonesia

19. Albay Islands, Philippines

20. Black Sand Beach, California

Did you know?

Sand is assessed using a particular criterion. Sand is defined as any substance in which more than 50% of the material has a diameter greater than 75 microns (.03 inches) but less than .18 inches. It is thought to be silt or clay if the average particle size is less, and garden-variety gravel if the average particle size is greater.


Hawaii is an amazing place to visit and the beaches are some of the best in the world.  Certainly the most unique and interesting are the black sand beaches.  Visiting them provides a very different beach experience and surely is one to not miss.


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