Dear O. Qutachi

Hello,

Mud is a mixture of clay minerals and all of them are natural ion ex-changer some of them are cat- ionic and the other are an- ionic , all clay minerals are a natural composite of Aluminum oxide (Alumina) and Silicon oxide and different minerals cat-ions , but Sand is Silicon  oxides (Silica) mixed with some metal oxides  and some metals sals.

Regards

Assistant Prof.

Mohammed H. Latif

University of Baghdad

 Yes -  clay, silt, sand are textural classes with particle diameter thresholds of normally 2 microns (between clay and silt) and 50 microns (between silt and sand). The coarsest sand is 2 mm (2000 microns) in diameter. The term 'mud' is used for mixtures of clay- and silt-sized material. Due to resistance to weathering, clay on the earth's surface is usually composed of layered alumino-silicates (residual minerals in chemical weathering process), while sand and silt are often quartz-rich ('end'-products of mechanical weathering). 

Hope this helps.

Though I completely agree with the statement that....clay, silt and sand are nothing but particle sizes, and can therefore have any kind of chemical composition.

But at the same time the mineral assemblage hence the chemical composition of all these three will have quite marked differentiation.

Sands in normal sense are composed of quite resistant minerals to weathering, predominantly composed of quartz, associated with feldspars and heavy minerals such as zircon, garnet, rutile, ilmenite, sillimanite, monazite, tourmaline, magnetite.

depending upon heavy mineral concentration their composition varies but certainly they are silica rich.

Clay again is predominantly composed of  clay minerals such as illite, kaolinite, monmorillonite and some chlorite, sericite, fine quartz+feldspar depending upon the provinance.

Accordingly the composition is dominated by Al2 O3 , some Fe and Mg.

Mud will be mostly a mixture of all the elements depending upon host rock composition.

It is true that clay, silt and sand are textural terms having any composition. It may dominates with silicon dioxide, carbonate, ferrugenous etc. and can therefore have any kind of chemical composition.

Clay is predominantly composed of  clay minerals such as kaolinite, illite, monmorillonite, chlorite, sericite etc. Clay is mainly alluminium rich whereas sand is dominated by SiO2. But mud is the mixture of clay with silt and even fine sand. In this respect mus is commonly rich in SiO2 than clay and sand is richer in that SiO2 than clay and mud.But chemical composition of all sand, clay or mud depends on provenance or source rock. It may vary widely. Hope it may help you.

The chemistry of clay is more complicated than the chemistry of sand

Many thanks for the valuable information. 

  Dear Dr. Qutachi:

normally I try and find an answer to a question raised. In this case I try and restore the question so that it might make sense and accord with what has been already told. The classification scheme of shales proposed by Lundegard and Samuels (1980) is the launching pad. It can be used from the non-indurated argillaceous sediments  through the mica schists. I omit those features (e.g. lamination, bed thickness etc..)  which do not respond to compositional changes especially for this  case and try and avoid any overload.

Silt: 0-32 % clay-sized constituents

Mud: 33-65 % clay-sized constituents

Clay (-mud): 66-100 % clay-sized constituents (< 0.063 mm)

It is evident that in silt Si is more abundant, whereas in clay it is Al which prevails. Ti tends to be present in heavy minerals and might increase towards the silt. Other major elements such as Fe and Mg may also vary in a similar way. It has to be noted, that this  classification has to be tested and calibrated  for the study area in question.

Irrespective of the goal of investigation, this is only a crude and quick method to get an overview. Any attempt to get a full-blown picture of sediments  based on chemical composition only is prone to a mis-interpretation.

I wish you much success

H.G.Dill

I agree with Mathias H. Köster: clay, silt and mud make reference to particle sizes, not chemical compositions. However, there is a group of silicated minerales named "clays" that includes Kaolinite Group, Smectite Group, Illite Group and others.

I totally agree with Mathias H. Köster and Catalina Martinez, check those groups of minerals. You can check the size constituents mentioned above.

Best regards