Clay Mineral Group

The Clay Minerals are a part of a general but important group within the phyllosilicates that contain large percentages of water trapped between their silicate sheets. Most clays are chemically and structurally analogous to other phyllosilicates but contain varying amounts of water and allow more substitution of their cations. There are many important uses and considerations of clay minerals. They are used in manufacturing, drilling, construction and paper production. They have geat importance to crop production as clays are a significant component of soils.


Clay minerals are divided into four major groups. These are the important clay mineral groups: 2 groups will be discussed here

The Kaolinite Group

This group has three members (kaolinite, dickite and nacrite) and a formula of Al2Si2O5(OH)4. The different minerals are polymorphs, meaning that they have the same chemistry but different structures (polymorph = many forms). The general structure of the kaolinite group is composed of silicate sheets (Si2O5) bonded to aluminum oxide/hydroxide layers (Al2(OH)4) called gibbsite layers. The silicate and gibbsite layers are tightly bonded together with only weak bonding existing between the s-g paired layers.Uses: In ceramics, as a filler for paint, rubber and plastics and the largest use is in the paper industry that uses kaolinite to produce a glossy paper such as is used in most magazines.

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The Montmorillonite/Smectite Group

This group is composed of several minerals including pyrophyllite, talc, vermiculite, sauconite, saponite, nontronite and montmorillonite They differ mostly in chemical content. The general formula is (Ca, Na, H)(Al, Mg, Fe, Zn)2(Si, Al)4O10(OH)2 - xH2O, where x represents the variable amount of water that members of this group could contain. Talc's formula, for example, is Mg3Si4O10(OH)2. The gibbsite layers of the kaolinite group can be replaced in this group by a similar layer that is analogous to the oxide brucite, (Mg2(OH)4). The structure of this group is composed of silicate layers sandwiching a gibbsite (or brucite) layer in between, in an s-g-s stacking sequence. The variable amounts of water molecules would lie between the s-g-s sandwiches.Uses: Are many and include a facial powder (talc), filler for paints and rubbers, an electrical, heat and acid resistant porcelain, in drilling muds and as a plasticizer in molding sands and other materials.

Is graphene a miracle material?

The material graphene was touted as "the next big thing" even before its pioneers were handed the Nobel Prize last year. Many believe it could spell the end for silicon and change the future of computers and other devices forever.
Graphene has been touted as the "miracle material" of the 21st Century.
Said to be the strongest material ever measured, an improvement upon and a replacement for silicon and the most conductive material known to man, its properties have sent the science world - and subsequently the media - into a spin.

WHAT IS GRAPHENE? Graphene is taken from graphite, which is made up of weakly bonded layers of carbon Graphene is composed of carbon atoms arranged in tightly bound hexagons just one atom thick Three million sheets of graphene on top of each other would be 1mm thick The band structure of graphite was first theorised and calculated by PR Wallace in 1947, though for it to exist in the real world was thought impossible Due to the timing of this discovery, some conspiracy theorists have linked it to materials at the Roswell "crash site" In 2004, teams including Andre Geim and Konstantin Novoselov demonstrated that single layers could be isolated, resulting in the award of the Nobel Prize for Physics in 2010 It is a good thermal and electric conductor and can be used to develop semiconductor circuits and computer parts. Experiments have shown it to be incredibly strong

"Our research establishes graphene as the strongest material ever measured, some 200 times stronger than structural steel," mechanical engineering professor James Hone, of Columbia University, said in a statement.
"It would take an elephant, balanced on a pencil, to break through a sheet of graphene the thickness of Saran Wrap [cling film]."
And the way this material can be utilised is as surprising as its properties.
"Graphene does not just have one application," says Professor Andre Geim, the current co-holder of the Nobel Prize in physics for his work with the material at Manchester University.
"It is not even one material. It is a huge range of materials. A good comparison would be to how plastics are used."
Much has been made of graphene's potential. It can be used for anything from composite materials - like how carbon-fibre is used currently - to electronics.
Since its properties were uncovered, more and more scientists have been keen to work on projects. About 200 companies and start-ups are now involved in research around graphene. In 2010, it was the subject of about 3,000 research papers.
And the benefits to both businesses and to the consumer are obvious - faster and cheaper devices which are thinner and flexible.
"You could theoretically roll up your iPhone and stick it behind your ear like a pencil," Professor James Tour, of Rice University, told the Technology Review.

We feel that it's rather difficult to imagine graphene as a replacement to silicon Dr Phaedon Avouris, IBM

If graphene can be compared to the way plastic is used today, everything from crisp packets to clothing could be digitised once the technology is established. The future could see credit cards contain as much processing power as your current smartphone.
"It can open completely new applications in transparent electronics, in flexible electronics and electronics that are much faster than today," says Jari Kinaret, professor of technology at Chalmers University in Sweden.
And beyond its digital applications, just one example of its use would be graphene powder added to tyres to make them stronger.