Clays are plastic due to particle size and geometry as well as water content, and become hard, brittle and non–plastic upon drying or firing.
Depending on the soil’s content in which it is found, clay can appear in various colours from white to dull grey or brown to deep orange-red.
What color is clay?
Clays that are tan, brown or brick in color contain iron oxide (terra cotta and stoneware) as the coloring agent. Clays that lack iron oxide are gray to white in color (porcelain). Note that another difference in clays is texture. Clays vary in particle size, and some are much coarser than others.
Why is some clay blue?
Ferrous iron is greenish blue and soluble. If you dig for clay in a wetland soils that are perpetually wet with poor water flow, you will find such reduced iron in your greenish-blue clay. Sediments with this color are called ‘gleyed.’ Because ferrous iron is soluble, it can leach out of clays, soils, and minerals.
Are there different types of clay?
Kinds of Clay
The three most common types of clay are earthenware, stoneware, and kaolin.
Where does clay come from?
Where does clay come from? Clay is a soft, loose, earthy material containing particles with a grain size of less than 4 micrometres (μm). It forms as a result of the weathering and erosion of rocks containing the mineral group feldspar (known as the ‘mother of clay’) over vast spans of time.