Marl or the other name Marlstone is a calcium carbonate non-clastic sedimentary rock. It has containt variable of clays and silt. The dominant carbonate mineral in the most of the marls calcite, aragonite, dolomite and siderite.  Iı belongs to the family of pelitic rocks (clays <0.02 mm, the fine particles in water sales) and a carbonate is a variety of mudstone. The rocks can be both chemical-biogenic and clastic orgin.The carbonate can be washed as detritus, usually to the carbonate skeleton of plankton or biochemically deposited calcite. In order to collect layers of calcite and clay sediments, which have become stronger over time in the seabed and compressed according to the weight of thrusting of younger sediments. In addition, the reaction of the sediment in the pore solution with mineral matter and sediment is gradually transformed into rock. Junk residual marble (also called landscape marble) means limestone and marl (as calcitic overprint mud stones).

Marls are whitish gray or brownish in color but can also be gray, green, red, or variegated. Greensand marls contain the green mineral glauconite, and red marls, iron oxides. Marl is much less easily split than shale and tends to break in blocks. Specimens are often nodular, and the nodules are usually better cemented than the surrounding rock.

Color: Green, brown, beige and gray – grayish white

Grain size: Very fine-grained

Texture: Conchoidal fracture

Minerals Composition: Calcite, Clay, Dolomite, Gypsum, Micas, Pyrite, Quartz

Marl Formation

It is a rock containing clay and calcium carbonate. It is formed from the erosion of other rocks during weathering; as rocks erode, small sedimentary particles–sand, silt, and clay–pile up on top of each other. Eventually, these sedimentary particles become compacted together to form a new rock. The type of new rock that is formed depends on the original rock that was eroded and on the nature of the erosion. If the new rock contains predominantly clay and calcium carbonate, it is called marl.

The most common use for marl is as a fertilizer for soils that are deficient in calcium carbonate (lime).

Where is Marl Located

Marl as lacustrine sediment is common in post-glacial lake-bed sediments, often found underlying peat bogs. It has been used as a soil conditioner and acid soil neutralizing agent.

Marl Uses

  • Decorative Aggregates, Floor Tiles
  • As Building Stone, Roof Tiles
  • Curbing
  • Cement Manufacture, Construction Aggregate, for Road Aggregate, Making natural cement, Raw material for the manufacture of mortar
  • Artifacts, Jewellery, Sculpture, Small Figurines
  • Creating Artwork, Soil Conditioner


Bonewitz, R. (2012). Rocks and minerals. 2nd ed. London: DK Publishing.