Topic about Eart Elements

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

2. Index
o Introduction
o 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
o Conclusion
o Bibliography

3. Introduction Of Elements
o 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.
o Elements cannot be broken down into simpler substances
by chemical method or physical method.
o 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
o Major elements usually measured in weight percentage and
are commonly above 1% of the chemical composition of the
material.
o Silicon and oxygen represents the bulk of Earth’s crust by
weight 75% and by volume 94.7%.
o The remaining 90% naturally occurring elements constitute
25% by weight and 5.3% by volume in the Earth’s crust.
o In addition to silicon and oxygen the other six major
elements include aluminium, iron, calcium, sodium,
potassium and magnesium.

6. Abundance Of Major Elements
o Major elements constitute the bulk of the Earth’s crust holding
99.2% by weight and 100% by volume.
o Oxygen and silicon bond together to be form the compound
SiO2 and are first and second most abundant elements
respectively.
o Most of the crustal minerals (~92%) are silicate minerals.
o Aluminium and iron are third and fourth most abundant
elements by weight in Earth’s crust.
o The eight major crustal elements – seven cation and one anion,
forms seven major oxides compounds in igneous rocks are
SiO2, Al2O3, FeO, MgO, Na2O, CaO, Na2O and K2O.

7. Distribution Of Major Elements In
Earth Crust

8. Behaviour OF Major Elements
o The chemical composition if any rocks mostly composed by the
major element which is divided in the term oxides.
1. SiO2 may exceed 99% in sandstone.
2. Al2O3 may reach nearly 70% in bauxite.
3. Fe2O3 up to 75% in limonite.
4. MgO is 20% in dolomite.
5. CaO is 56% impure limestone.

9. Trace Elements
o Trace elements are those which occur in very low concentration in common rocks.
o This trace elements generally of less percentage (<0.1%) by weight , hence they
are expressed in PPM. i.e chromium = 150PPM in crustal rocks.
o In addition to this trace elements occurs in minor quantity and these are known as
minor elements.
o 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).
o Trace elements are observed only in few minerals. They are useful in identifying
the magmatic differentiation and source of magma.
o E.g. Ultramafic rocks show more Ni and Cr, acidic igneous rock indicates Zr and
Rb
o 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
o 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.
o 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
o Relative abundance of compatible and incompatible trace
elements provide important information related to the
melting history of igneous rocks.
o 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.
o The residual rock from which partial melt have been removed
are enriched in compatible elements.

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

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

15. Conclusion
o Every thing in earth crust made up of elements.
o Abundance of Major elements in the rock composition
is more than 90%.
o Major elements are also very chief elements.
o 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.
o 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

17. Thank You