Dear Dr. Adikaram,

the term major or minor element can hardly be quantitatively be defined, particularly for an element which pertains geochemically to the top-ten elements making up the crust. There are figures between 1 and 5 wt. % to qualify for a minor element and above to be a major one but this depends on the chemical setting. As mineralogist dealing with the basic entity of rocks and ores I have established my own classification scheme. A major element is relevant in the crystal structure for the build up of a mineral. In pyrrhotite S and Fe are the major elements making up 38 and 62 %, respectively, in the Fe 0.95 S lattice. In sphalerite ZnS (ideal formula) may be present as a minor element , e.g., Zn 0.95 Fe 0.05 S (= 64 % Zn, 3 % Fe, 33 % S). It has no influence on the crystal structure. The Fe content may decrease to less than 1 % and substituted for by Cd, Hg, In, Ge, Mn, Ga and increase to 10 % ("marmatite") it is still not relevant for a different naming of the chemical compound and the structure does not change.

The classification depends on your geological/ mineralogical environment. In some soils typical of ferrircretes and laterites it is a major element while in a soil on calcareous bedrock it might be a minor element. The same holds true for sediments. Grading into oolithic Fe ore, iron is without any doubt handled as a major element because it is the element targeted upon whereas in salt minerals Fe forming a chromophore is a trace element.

Ask yourself what role is Fe going to play in the environment under consideration then you will get an idea whether Fe is to be considered as a major or minor element.

Any universal definition is fraught with a lot problems. I hope it was of help for you

H.G.Dill

Dear Sir,

I agree with you. Actually in Mn also we are facing the same problem.

So the classification is hardly acceptable for all cases.

Thank you very much for your answer.

Madurya

totally agree

Prof. Harald Dill has put it very well with examples and I do not think I can say any thing more.

Dear all: prof. Dill’s answer is very clear, but I might add one more example, potassium. K is a major element in continental crust, a minor element in oceanic crust and, in normal non metasomatized mantle, a trace. All common elements can be considered as such in different rocks, exceptions are those of higher periods, and some crucial light ones like Li, Be, B, and P. Mn in all normal rock is a minor element, but in some marine sediments and laterites could be a mejor element. Only very pure limestones or dolostones, and quartx- rich sandstones have trace Fe. Regards, Sebastian.

In short: The terms - major element, minor element, trace element, ultratrace element are not features of a given element, but features of the chemical composition of the given geological object.

Thank you all for your answers.

I quite support the answer from professor Harald G. Dill, the environment and the types of rocks and sediments someone is working on will determine whether to classify as major or minor elements

I'm in agree with Dr. Grande comment.

Fe could be considered as Major, minor of trace element by considering investigated environment.