Major Trace and Ree

Topic about Eart Elements

1. Major Traces and Rare Earth Elements Under The Guidance Of By :- Akash Naik Dr. P.K. Jain M.Sc. 1 st year S.O.S Earth Science School Of Studies In Earth Science Jiwaji University, Gwalior

2. Index Introduction Types Of Elements Major Elements and Its Abundance, Distribution and Behaviour Trace Elements and Its Types and Significance Rare Earth Elements and Its Distribution and Behaviour Conclusion Bibliography

3. Introduction Of Elements An element is composed of atoms that has same atomic number, each atom has the same number of protons in its nucleus as all other atoms of that element. Elements cannot be broken down into simpler substances by chemical method or physical method. Elements can only be changed in to other elements using nuclear methods.

4. Types Of Elements Different type of elements occurs in different concentration in earth crust. 1.Major Elements 2.Trace Elements 3.Rare Earth Elements (REE)

5. Major Elements Major elements usually measured in weight percentage and are commonly above 1% of the chemical composition of the material. Silicon and oxygen represents the bulk of Earth’s crust by weight 75% and by volume 94.7%. The remaining 90% naturally occurring elements constitute 25% by weight and 5.3% by volume in the Earth’s crust. In addition to silicon and oxygen the other six major elements include aluminium, iron, calcium, sodium, potassium and magnesium.

6. Abundance Of Major Elements Major elements constitute the bulk of the Earth’s crust holding 99.2% by weight and 100% by volume. Oxygen and silicon bond together to be form the compound SiO 2 and are first and second most abundant elements respectively. Most of the crustal minerals (~92%) are silicate minerals. Aluminium and iron are third and fourth most abundant elements by weight in Earth’s crust. The eight major crustal elements – seven cation and one anion, forms seven major oxides compounds in igneous rocks are SiO 2 , Al 2 O 3 , FeO, MgO, Na 2 O, CaO, Na 2 O and K 2 O.

7. Distribution Of Major Elements In Earth Crust

8. Behaviour OF Major Elements The chemical composition if any rocks mostly composed by the major element which is divided in the term oxides. 1. SiO 2 may exceed 99% in sandstone. 2. Al 2 O 3 may reach nearly 70% in bauxite. 3. Fe 2 O 3 up to 75% in limonite. 4. MgO is 20% in dolomite. 5. CaO is 56% impure limestone.

9. Trace Elements Trace elements are those which occur in very low concentration in common rocks. This trace elements generally of less percentage (<0.1%) by weight , hence they are expressed in PPM. i.e chromium = 150PPM in crustal rocks. In addition to this trace elements occurs in minor quantity and these are known as minor elements. They are basically Gallium(Ga), Chromium(Cr), Molybdenum(Mo), Lithium(Li), Nickel(Ni), Cobalt(Co), Copper(Cu), Zircon(Zr), Yttrium(Y), Platinum(Pt), Lanthanum(La), Strontium(Sr), Barium(Ba), Rubidium(Rb). Trace elements are observed only in few minerals. They are useful in identifying the magmatic differentiation and source of magma. E.g. Ultramafic rocks show more Ni and Cr, acidic igneous rock indicates Zr and Rb Trace elements during crystallization of magma gets substituted for a major elements in the structure or they remains in the magma.

10. Types Of Trace Elements Incompatible elements : Potassium(K), Rubidium(Rb), Caesium(Cs), Trotactinium(Ta), Niobium(Nb), Uranium(U), Thorium(Th), Yttrium(Y), Hafnium(Hf), Zircon(Zr) most have a large ionic radius. Do not fit easily into crystal structures and their bonds are easily broken. Are mobile, that they tend to migrate from crystal structures into the melt, when the rock is partial melting. Compatible elements : Nickel(Ni), Chromium(Cr), Cobalt(Co), Vanadium(V) and Scandium(Sc) which have smaller ionic radii. Fit easily into the crystal structure. Are immobile that they do not readily migrate from crystal structure.

11. Significance Of Trace Elements Relative abundance of compatible and incompatible trace elements provide important information related to the melting history of igneous rocks. With small degree of partial melting incompatible elements are depleted in the residual rock and enriched in magma that migrate up toward the earth surface. The residual rock from which partial melt have been removed are enriched in compatible elements.

12. Rare Earth Elements Rare earth elements are a set of 17 chemical elements in the periodic table , specially the 15 lanthanides plus scandium and yttrium. Are divided into heavy and light rare earth element. Heavy rare earth element includes La, Ce, Nd, Pm and Sm. Rather elements are the light rare elements.

13. Distribution Of REE When we look at the periodic table there is a lack of two rows of element located below the main body of the chart, these element are La(57) and Ac(71).The Lanthanide series is also called rare earth elements. The rare earth metal found in group of ‘3’ of the periodic table under VI and VII PERIODIC (5D and 5F) electronic configuration.

14. Behaviour of REE The REE are silvery, silvery white or grey metal. REE are late crystallizing elements because of higher ionic radii. The metal has high electrical conductivity. REE are founded with non metal usually in the 3 rd oxidation state. They not easily mix-up.

15. Conclusion Every thing in earth crust made up of elements. Abundance of Major elements in the rock composition is more than 90%. Major elements are also very chief elements. Trace elements may be may not be present in any rock or minerals, then presence and absence in the particular rock and minerals play vary crucial role to find out the crystal history or particular rock minerals. Rare Earth Elements (REE) composition are vary rare in any rock composition.

16. Bibliography Principle of Geochemistry by Brian Mason and Carleton B. Moore L.R. Wager (The distribution of trace elements) 1951 - sciencedirect.com

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