Biogenic sand

Biogenic sand is composed of exoskeleton or bone fragments of dead sea (usually) creatures. This sand is widespread in low latitude (less than 35°) beaches.

There are many different organisms that can contribute to the formation of this sand type and therefore one biogenic sand may greatly differ from another. Biogenic sand is usually light-colored and its components are usually made of carbonate material although some organisms prefer silica.

Important source material are the remains of clams, sea snails, foraminifera, algae, corals, echinoids, sponges, etc. Sand may consist of up to 100 percent of biogenic grains but mixtures of mineral and biogenic grains are common also.

A sand sample consisting of corals and foraminifera from Bermuda.
Coral sand
Biogenic sand (forams, corals) from Molokai, Hawai’i.
Majorca biogenic sand
Biogenic grains from Majorca, Spain.
Biogenic grainsZakynthos biogenous sand grains
Biogenic grains from Zakynthos, Greece.
Globigerina ooze
Globigerina ooze covers large areas of ocean floor. These forams are gathered from the seafloor of the Weddell Sea (3500 meters below sea level) near Antarctica. Red circles are around Orbulina universa, green could be Rotaliida, and yellow ones are Globigerina but some of them may be Neopachyderma also. Width of view 5.1 mm.
Biogenic sand maerls
Fine-grained biogenic sand consisting of red algae, sponge spicules, sea urchin spines, clams, sea snails, and foraminifers that occur close to maerl deposits. Dog’s Bay, Ireland. Width of view 5 mm.
Coarse maerl
Coarse-grained maerl composed of red algae but also clams, sea snails, and quartz grains. North Sound, Greatman’s bay, Ireland. Width of view 15 mm.

2 thoughts on “Biogenic sand”

  1. Have you ever come across a sand , with grains as big as long grain white rice, and each grain has a small black spot.? found in floor of jungle swamp.

Leave a Comment