11 Incredible Rocks, Gems, and Crystals Found in the Ocean (With Photos)

By Dr. Keith Jackson - Geology PhD

| Updated

11 Incredible Rocks, Gems, and Crystals Found in the Ocean (With Photos)

By Dr. Keith Jackson - Geology PhD


The ocean is home to many treasures, including a variety of gems and crystals. Pearls, quartz, and ocean jasper are just some of what can be found beneath the waves and along the beach.

These natural beauties come from different parts of the ocean, from shallow waters to deep sea beds. Exploring the ocean can reveal these gems, showing the wide range of colors and forms nature creates.

The Gems and Crystals You Can Find in the Ocean

The ocean is like a big treasure chest, full of surprises waiting to be discovered. It holds many secrets under its waves, including some pretty cool stuff. We’re going to take a closer look at what kinds of treasures the ocean hides.


two white baroque pearls
Pearls provided by SoulrellePearls

Pearls have a soft, shiny appearance that comes in various colors, like white, pink, and even black. They’re not as hard as some other gems, which means they need to be taken care of to keep their smooth surface and shine.

Pearls are made by oysters and some other mollusks as a way to protect themselves against something irritating, like a piece of sand. This process happens over time, layer by layer, inside the shell until the pearl is formed.

You can find pearls in both saltwater and freshwater environments around the world. Divers go into the water to collect pearl oysters or mussels, and sometimes they’re farmed in pearl farms where conditions are perfect for making pearls.


iridescent inside of an abalone shell
Abalone provided by Mistiquora

Abalone shells are known for their stunning colors, ranging from blue and green to pink and purple, with an iridescent shine. This makes them ideal for jewelry and decorative items.

Abalones are sea creatures that need rocky, coastal waters where they can cling onto surfaces and feed on seaweed. These conditions are crucial for their growth and the development of their colorful shells.

You can find abalones in many parts of the world, especially in cool waters along coastlines. Divers carefully collect them by hand from rocky underwater areas, ensuring not to harm the marine environment.


round smoothened quartz pebble
Quartz provided by LostCoastPebbles

Quartz is a crystal that can be clear or come in colors like pink, purple, and even black. It’s very hard, making it scratch-resistant, and has a glassy shine.

This mineral forms from cooling magma and in areas where hot, mineral-rich water circulates through rock cracks. Over time, the minerals deposit and crystallize into quartz in these environments.

While quartz is not typically found in the ocean, it can be discovered on beaches and in coastal areas where it has been washed down by rivers.

You can find quartz by searching along these beaches, especially after storms, which can uncover and wash up new quartz pieces.


white dry coral
Coral provided by seashellmart101

Coral comes in a variety of colors like white, pink, or red over time. When coral dies, it leaves behind its hard skeleton, which continues to contribute to the reef’s structure.

This skeleton is much harder than live coral, making it durable enough for jewelry and decorations, but it still has a porous, rough texture.

Coral reefs grow in warm, shallow waters where sunlight can reach them, forming from the skeletons of tiny sea creatures over thousands of years.

While collecting dead coral is sometimes allowed, it’s important to do so responsibly to avoid harming the delicate balance of reef ecosystems.


green and brown serpentine slab
Serpentine provided by Fossilera

Serpentine is a fascinating mineral that comes in shades of green, yellow, and sometimes even black or white. It’s softer than many gemstones, making it easy to carve into shapes but also means it scratches more easily.

This mineral forms deep in the Earth’s crust where oceanic plates are pushed under continental plates, a process called subduction. The intense heat and pressure in these zones transform rocks into serpentine.

Serpentine can be found near areas with past or present volcanic activity. It’s usually mined from the ground in these areas.


several raw agate pebbles
Agate provided by BlueWaterTreasuresNW

Agate is a colorful stone, often found with bands of different colors like red, brown, white, and yellow. It’s pretty hard, which makes it great for making jewelry and other decorative items that last a long time.

Agate forms when silica from groundwater fills cavities in rocks, layer by layer, over thousands of years. These conditions are most common in volcanic areas where the rock has lots of holes and gaps.

While agate isn’t typically found in the ocean, it can be discovered on beaches and coastal areas where volcanic activity has occurred. 

You can collect agate by searching along these beaches, where the stones can be spotted mixed in with other pebbles and sand.


purple and white tumbled amethyst pebbles
Amethyst provided by RockAndTumbleCo

Amethyst is known for its beautiful purple color, which can range from a light lavender to a deep violet. It’s quite hard, making it suitable for all sorts of jewelry, and it often has a clear, translucent quality that lets light shine through.

This gemstone forms inside hollow rocks, as a result of volcanic activity, when gas bubbles in lava cool and create cavities that are then filled with mineral-rich water. Over time, the minerals crystallize into amethyst.

Amethyst can be discovered in coastal areas close to volcanic activity. You might find them hidden in rocks or in loose crystals along the beach.


raw beige limestone
Limestone provided by MyUnderwaterGarden

Limestone is a rock that can be found in a range of colors, from white to gray to tan. It’s not very hard, which makes it easy to cut into blocks or carve, but it doesn’t have clarity like crystals or gems because it’s opaque.

This rock forms under the sea or in shallow waters when shells, corals, and other marine organisms that are made of calcium carbonate pile up and compress over millions of years.

The pressure and chemical reactions turn these accumulations into solid limestone.

Limestone deposits can be found in oceanic shelf areas and on land that was once under the sea. People quarry limestone directly from these deposits, using large machines to cut it into usable blocks or slabs.

Ocean Jasper

oval white and blue-green ocean jasper
Ocean jasper provided by rockmysoulminerals

Ocean jasper is a colorful stone, full of swirling patterns in shades of green, pink, red, black, and white. It’s pretty hard, making it durable for use in jewelry and decorations, and its polished surface has a nice, smooth feel.

This type of jasper is formed from volcanic ash and silica, which gets deposited into the cracks and cavities of rocks. Over time, this mixture hardens into the beautiful patterns that make ocean jasper so unique.

Ocean jasper is only found in one place in the world, along the coast of Madagascar, where it’s washed by the ocean. You’ll have to wait for low tide to gather the stones from the shallow waters, making it a rare and sought-after gem.


bright green olivine (peridot) pieces
Olivine (peridot) provided by Infinitygems69

Olivine is a gemstone that shines in shades of green, from olive to bright green, which is how it got its name. It’s quite hard, making it resistant to scratches, and it often has a cloudy or opaque look.

This mineral forms deep inside the Earth’s mantle and comes to the surface during volcanic eruptions. The presence of iron and magnesium in olivine gives it its green color, and it’s commonly found in basalt, a type of volcanic rock.

Olivine can sometimes be found in the ocean, especially near volcanic islands where eruptions have occurred. It can be collected from beaches or mined from areas where volcanic activity has brought it to the surface.

Sea Glass

pale blue to green-blue sea glass pieces
Sea glass provided by PRBeachy

Sea glass is made from pieces of broken glass that have been smoothed and frosted by years of tumbling in the ocean. It comes in many colors, like green, blue, brown, and sometimes rare shades like red or yellow.

There aren’t geological conditions for forming sea glass like there are for natural gems because sea glass starts as human-made glass.

Instead, it’s the movement of the ocean, sand, and rocks that slowly wears down the glass, turning sharp shards into smooth pieces.

You can find sea glass along beaches and shores, especially in areas known for strong tides and waves. People collect it by walking along the beach, looking near the high tide line or where waves deposit debris.

About Dr. Keith Jackson - Geology PhD

Keith Jackson is an avid rockhound who is constantly exploring new sites to expand his collection. He has worked as a professional Geologist for over 20 years and holds a PhD in Geology from the University of Nebraska-Lincoln, a Masters Degree in Geology from the University of Nebraska-Lincoln, and a Bachelors Degree in Geology from the University of Connecticut.

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