Clays occupy a very special place in the peloid group. They are a natural source of minerals, and because of this clays have been used by humans and animals since life on Earth began. Animals are instinctively drawn to clay - they cover themselves to treat sores, protect themselves from infection, they eat it to stock up on minerals. Humans who have preserved the knowledge and traditions of their ancestors have been doing it too to keep themselves healthy and free from disease and parasites. Clay eating (geophagy) has been practised by humans all over the world for thousands of years, and is experiencing a great revival these days.

There are many therapeutic uses attributed to clay, most of them connected to its ability to expand and absorb, as well as adsorb harmful substances from the body (detoxifying effect). Clay can swell up to 45% due to its absorption capacity. Another very important quality of clay is ionic exchange. To put it simply, clay has the ability to take from the body the elements it does not need replacing them with the ones it does need. The most widely used are bentonite clays (sodium and calcium), as well as French montmorillonite and Illite clays. There are also other very popular types.

Here is what Wikipedia Free Encyclopaedia says about clay:

“Clay is a generic term for an aggregate of hydrous silicate particles less than 2micrometres in diameter. Clay consists of a variety of phyllosilicate minerals rich in silicon and aluminium oxides and hydroxides which include variable amounts of structural water. Clays are generally formed by the chemical weathering of silicate-bearing rocks by carbonic acid, but some are formed by hydrothermal activity. Clays are distinguished from other small particles present in soils such as silt by their small size, flake or layered shape, affinity for water and high plasticity index ...

Montmorillonite, with a chemical formula of (Na,Ca)0.33(Al,Mg)2Si4O10(OH)2·nH2O, is typically formed as a weathering product of low silica rocks. Montmorillonite is a member of the smectite group and a major component of bentonite “. http://en.wikipedia.org/wiki/Clay

Clay is a plentiful material: any soil sample may contain a few clay particles. Clay's mineral properties establish the size of the clay particle. Clay minerals are silicate crystals that are so fine-grained they’re really micro crystals, meaning that they’re easily absorbed by the human body.

In general, clays contain about fifteen minerals, and many more trace minerals. In the basic fifteen minerals, a typical element such as magnesium may be the dominant component. It can be replaced by aluminium or possibly iron, or any single mineral substance since it becomes an active or rotating ion, which creates an energy field around it. This occurs as the molecules of a single mineral break into its simpler constituents, or as two interacting minerals exchange a portion of their constituents.

Any of the basic groups may be replaced by another substance until the mineral structure is essentially balanced electrically. The extent to which the clay mineral ions become active determines the clay's definition as "living clay". This may be accomplished by the addition of a molecule of water if the clay mineral has been created in such a way as to contain a charge.

Calcium Montmorillonite clay is reported to contain no less than 67 minerals. This impressive assortment of minerals includes calcium, iron, magnesium, potassium, manganese, and silica as well as trace elements, those appearing in very tiny amounts.

Clays differ in colour. The colour of clay is normally determined by the presence of various minerals. Clay is valued on the basis of montmorillonite percentage it contains, since Calcium montmorillonite is the mineral compound which gives clays the ability to expand up to many times its size through the process of absorption and adsorption.

Classification of clay

Following information is quoted from California Earth Mineral Corporation website http://www.calearthminerals.com/claytypes.htm: "In a clay mineral the elements (oxygen, silicon, potassium, etc.) are spheres arranged in a regular three-dimensional pattern. The spheres are the building blocks of the clay mineral, and the arrangement of the spheres determines the type of mineral. The character of the clay mineral group determines the type of clay and its eventual use. In other words, the clay mineral structure gives us an understanding of its specific properties. The three-dimensional pattern of the clay mineral. Whatever sits in the middle, in this case the silica element, determines the type of clay and what it will do. The name of this mineral structure is single silica tetrhedron, and it is the building block of montmorillonite clay (the best for eating).

Among the clays suitable for eating, montmorillonite is the most common and most sought after. It has been the subject of many research studies and has long been recognized by scientist and laypersons for its unusual properties. Montmorillonite clay was named after the town of Montmorillon, France, where it was first identified. The mineral clay belongs to a group of clays known as smectite, a word that describes its layered structure. The smectites are one of seven clay mineral groups. Each group contains a certain number of species, variations on the layered structure. Clay minerals come in many different shapes and sizes to produce a wide variety of clays.

Because there are so many types of clay, not all of them share the same function. Some are more suited for industrial use whereas others are suited for dietary use.

There are seven groups of clay:

• The Kaolin group

• The Illite group

• The Smectite group

• The Chlorite group

• The Vermiculite group

• The Mixed-layer group (consists of all five groups above)

• Lath-form group

All clays will adsorb; however, the smectite group is the only group capable of absorption. Most clays sold in the health food industry belong to the smectite category.

Kaolin

While it absorbs toxins and bacteria like the other clays, it primarily acts as a bulking agent and in anti-diarrhoeal medications. Some companies add kaolin to food supplement due to its mineral content.

Illite

The illite group is named for the state of Illinois. The best-known species of illite is glauconite (a green mineral clay). It is typically found in clays of marine origin. Other colors include white and yellow.

Smectite

Smectite is characterized by its expandable properties. Unlike all the other clays, only smectite can absorb toxins. This qualifies its structural uniqueness and sets it apart from all other clays. For this reason, smectite has become a favorite clay for industrial and dietary use. The most familiar species of smectite is montmorillonite. Again, it is the most preferred species of edible clay. Most clay research has been done with montmorillonite.

What makes montmorillonite so special?

The montmorillonite minerals occur in very small micron sized particles. They are extremely fine-grained and thin-layered, more than any of the other clay minerals. The layers contain ions that are very loosely bound to one another and easily exchangeable. Not only will the toxins stick to its outside surface, but numerous elements and organic matter will enter the space between the layers.

In addition to its already unique structure, montmorillonite has a particularly large surface area when properly hydrated in water, which further boosts its adsorptive and absorptive properties. Chemically and structurally, it is shaped like a credit card, with negative charges on the flat surface and positive charges on the edges. Therefore, the negative charge (the good one) is many times more powerful that the positive charge. Montmorillonite is a more complicated clay and has a higher exchange capacity than the simpler species of clay, such as kaolinite. Its ability to adsorb and absorb toxins is greater than that of the clays in the other groups.

According to one article on clay (Lei 1996), a mineralogist at Massachusetts Institute of Technology, Robert T. Marin, stated that one gram of this clay has a surface area of 800 square meters. To give that some serious perspective, that's about ten football fields! The greater the surface area of the clay, the greater the power to pick up the positively charged particles or toxins many times its own weight.

Any given clay is usually a mixture of clay minerals, one or two minerals almost always being predominant. Clays are rarely found separately and are usually mixed not only with other clays but with microscopic crystals of quartz, mica, feldspar, and carbonates. Most clay contains montmorillonite to a greater or lesser degree. The available types of montmorillonite vary in color, consistency, and shape. The color may be white, gray, or tan, with tints of yellow or green. Typically, montmorillonite will be included in a mixture of clay groups in any given material; all six groups will most likely contain particles of montmorillonite.

Bentonite Sodium bentonite is a commonly and highly utilized industrial clay. Currently, several companies are selling calcium bentonite in health formulas. Bentonite is widely distributed in nature. Its name was derived from the Fort Benton series of cretaceous rocks in Wyoming, where it was first found. The name can be misleading; sodium-bentonite is not a mineral name but a trade name for a commercially sold swelling clay. It is often used in commerce as a name for montmorillonite, and sometimes the names are used interchangeably. Smectite is the general group name used by mineralogists.

The source of bentonite is weathered volcanic ash. In marine environments, the ash transforms itself, over time, to smectite. There are several species in the smectite group, montmorillonite being one of them. Depending on its source, bentonite may contain a high percentage of montmorillonite or just a tiny bit. The rest of the contents may either be related or a completely different mineral group. Rarely does 100 percent pure smectite occur: therefore, not all bentonite is a pure smectite. Quite commonly, the clay minerals illite or chlorite are present in alternating layers.

When choosing the right clay to eat, be aware of this. Bentonite is sometimes wrongly sold under the montmorillonite label or, at least, the name doesn't give any clear indication of its contents. There are a wide variety of bentonite clays that looked, felt, tasted, and acted differently from the others. They did so because they were not the same clays. The variation in minerals does not really matter in industrial use, so long as the bentonite has good expansion capacity. But the guidelines for industry use do not hold for the consumption of clay. Unfortunately, because some clays vary in contents, some are better suited than others for eating.

This tends to be confusing, and it seems uncertain exactly which clay mineral is actually aquired even when the label says "bentonite". Even the scientists have differing opinions or are not sure themselves.

Single-and Mixed-Clay Minerals

Typically, any given clay material may be composed of particles of a single clay mineral or a complex of many different naturally occurring minerals. It is not easy to find pure samples of many clay minerals. When they are found in nature, like a vein of gold, they are painstakingly mined. Otherwise, scientists depend on preparing single-clay minerals in the laboratory.

Most commonly in nature, layers of one type - for example, montmorillonite - are interlayered with units of another type, for example, illite. In other words, a tiny particle may be composed of successive layers of illite and montmorillonite. This of course varies according to the region of the deposit and the climate. Climatic effects influence the occurrence of certain minerals. http://www.calearthminerals.com/claytypes.htm

How does clay absorb and adsorb other substances?

The reason for this is that the clay's minerals are negatively charged while toxins tend to be positively charged; hence the clay's attraction works like a magnet drawing metal shavings. But it is even more involved than that. Once hydrated (combined with water), Bentonite has an enormous surface area. Bentonite is made of a great number of tiny platelets, with negative electrical charges on their flat surfaces and positive charges on their edges. When bentonite absorbs water and swells, it is stretched open like a highly porous sponge; the toxins are drawn into these spaces by electrical attraction and bound fast.” Dr. Bernard Jensen,”Guide to Diet and Detoxification”. According to the Canadian Journal of Microbiology (31 [1985], 50-53), clay can absorb pathogenic viruses, aflatoxin (a mold), and pesticides and herbicides. Ingested clay is eventually eliminated from the body with the toxins bound to its multiple surfaces.

Bentonite, a medicinal powdered clay which is also known as montmorillonite, derives from deposits of weathered volcanic ash. It is one of the most effective natural intestinal detoxifying agents available and has been recognized as such for centuries by native peoples around the world. Whatever the name, liquid clay contains minerals that, once inside the gastrointestinal tract, are able to absorb toxins and deliver mineral nutrients to an impressive degree, says Knishinsky. Liquid clay is inert which means it passes through the body undigested. It first adsorbs toxins (heavy metals, free radicals, pesticides), attracting them to its extensive surface area where they adhere like flies to sticky paper; then it absorbs the toxins, taking them in the way a sponge mops up a kitchen counter mess. Dr. Bernard Jensen, "Guide to Diet and Detoxification"