Claystone is a cousin of siltstone and mudstone in particle size. Thereby, the formation of claystone is akin and useful like mudstone in the industry. World of Stones USA is giving fine clues of applications and facts about the claystone.

By definition, claystone is a clastic type of sedimentary rock. It chiefly consists of fine particles of less than 1/256mm size, which are cemented into hard rock. 

In general, people use mudstone, siltstone/shales, and claystone terms interchangeably. However, all are different things at geology perspectives. Let’s know the facts first.

How to Distinguish Claystone?


Shales or siltstone is containing more than half of the composition made from silt-sized particles, such as

  • Coarse silt – 1/32mm (5Phi-Ø)
  • Fine silt – 1/64mm (6Phi-Ø)
  • Very fine silt – 1/128mm (7Phi-Ø)

Siltstone breaks into thin chips, which are roughly parallel from top to bottom.


Claystone is containing more than half of the composition made from clay-sized particles – 1/256mm (8Phi-Ø). We will see more details in the next section.


It is a mixture of silt and clay size particles and forms a bit hardened mud. Mudstone breaks into rocky pieces. 

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Geological Definition & Classification of Claystone:

At the geological perspectives, claystone can define in the following ways. 

Class Sedimentary rocks
Sub-class Durable & medium hardness rock
Categories Fine-grained & opaque rock
Types Lithified and non-fissile rocks
Species 35 recognized clay minerals exist.

The texture of Claystone: 

Texture Clastic
Color  Black, Blue, Brown, Green, Grey, Orange, Red, White, Yellow, 
Durability  Durable 
Water-resistant  Yes 
Scratch-resistant  Yes 
Stain-resistant  No 
Acid-resistant  No 
Wind resistant  No 
Appearance  Rough & Dull 

Properties of Claystone:

At the general and geological perspectives, claystone has the following properties. 

Hardness 3.5 to 4.0
Grain size Less than 1/256mm
Streak White
Porosity Less
Toughness 2.6
Cleavage  Perfect
Density 2 to 2.9 G/cm3
Specific Heat Capacity 0.92 KL/Kg K
Resistance Heat & Impact 

Composition of Claystone:

Mineral content Biotite, Chlorite, Feldspar, Micas, Muscovite or Illite, Plagioclase, Pyrite, & Quartz
Compound content Aluminum Oxide, Ca, NaCl, CaO, Iron(III) Oxide, MgO, & Silicon Dioxide
Weathering Biological Weathering, Chemical Weathering, & Mechanical Weathering
Erosion  Coastal erosion, water erosion & wind erosion
Formation It is soft but can be hard and brittle. Formation takes place due to the weathering of mudstone.

Reserves of Claystone: 

Claystone availability is universal and found mainly in the following regions and countries.

Bald Hill at Long Reef. New South Wales, Australia

Asia India, China, Bangladesh, & Russia
Africa South Africa, Ethiopia, Tanzania, Morocco, & Kenya
Europe Scotland, France, Austria, Germany, Italy, Greece, Spain, Romania, & Switzerland
North America Canada, Panama, & USA
South America Colombia, Bolivia, Chile, Peru, Ecuador, & Venezuela
Australia New South Wales, New Zealand, Queensland, Victoria, Western Australia

Katoomba, Australia

Claystone Formation:

Clay particles are fine-grained and nearly 1/1000 times finer than a normal sand particle of 1mm size. When water flows, it carries claystone particles 100 times farther than the sand particles.

Moreover, the sedimentation of claystone particles requires a relatively calm milieu at the water basins in the river and sea. Thereby, due to heavyweight sandstone found at deeper layers of sediment strata. 

Whereas thin layers of the claystone found on the top and mostly in between siltstone layers. It is due to almost similar particle sizes of siltstone and claystone.

Applications of Claystone: 

Claystone has an interior as well as exterior applications in the construction industry. Architects also prefer claystone in the creation of decent curbing appeal. Apart from these, manufacturing applications of claystone is far wider than we anticipate it in the direct constructions.

For instance, 

  • Claystone is useful in the steel industry to process Iron Ore by acting as a sintering agent.
  • Claystone provides raw material in cement manufacturing units to make natural cement and create the mortar.
  • Claystone is proving good stone aggregate material for the road building industry.

Let’s see some good examples of the applications of claystone in a direct construction.

Claystone Aggregates in Interior & Exterior Decoration:

Claystone Aggregates in Garden Decoration: You can use claystone aggregates, pebbles, and boulders to decorate your interior and exterior spaces like wall coverings, floors, and window sills. You will find claystone aggregates and pebbles in various shapes and colors, albeit all with the natural beauty!

Claystone Aggregates in Garden Decoration:

You can decorate your garden with claystone pebbles and stone aggregates. Paths, planters, and decorative pieces of the garden landscape are ideal spaces to use colorful claystone pebbles and aggregate to beautify your gardens and outdoor landscapes.

Claystone as Facing Stone:

Claystone Facing Bricks

Bricks from claystone is a modern approach in the construction industry, and China is famous for it. Many stone veneer producers create claystone veneers as facing bricks and provide a decent opportunity to décor your exterior facing walls.

Claystone in Entryway:

Claystone Raw Tiles Claystone Façade 

Raw claystone tiles were used in ancient days, and many have kept the tradition alive by decorating their façade with claystone tiles right from floors to entryway and even on the walls to match a theme. Claystone powder also in fashion to decorate exterior walls to create classic look-n-feel.

Claystone in Roofing: 

Like slatestone, many areas in Asian countries are using claystone roof tiles in very primitive formats. Such traditions help people in many ways to leverage natural offerings of claystone material.

Find Your Claystone Inventory:

World of Stones USA has a big stock of claystone inventory to use in your modern construction and give a classic touch augmenting aesthetic appeal. You can find the best stone consulting services to know where you can apply claystone in your next project and how it could be a feasible adventure for you. Our claystone products are available across the States thanks to our expanded distribution network and a big list of distributors. 

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