Geochemical Classification of Elements Questions and Answers

Q: Elements that form ions with higher charge than the +2 found for the Mg+2 Fe+2 and Ca+2 present in the octahedral sites in mafic and ultramafic rock forming minerals and are larger in size than the tetrahedral Si4+ and Al3+ sites in silicate minerals are termed as :

They are the high field strength elements (HFSE).HFSE such as Zr, Hf, Nb, Ta and Ti form small ions with high charge (+3 to +5 and more), so their ratio of charge to radius, the field strength, is high. Their charge is too great for the octahedral sites occupied by Mg2+, Fe2+ and Ca2+, and they are too big for the tetrahedral sites of Si and Al, so they behave as incompatible elements.Large ion lithophile elements (K, Rb, Cs, Sr, Ba) are incompatible for the opposite reason: large ions with low charge. Transition metals such as Ni and Cr fit readily into octahedral sites, and heavy rare earth elements are a separate group defined by atomic number.

Q: Lithophile elements show affinity for :

Lithophile elements show affinity for the silicate phase.In Goldschmidt's geochemical classification, lithophile ('rock-loving') elements, such as Na, K, Ca, Mg, Al, Si, the rare earths and U, combine readily with oxygen and concentrate in silicate minerals of the crust and mantle.Chalcophile elements (Cu, Zn, Pb) prefer the sulphide phase, siderophile elements (Fe, Ni, Pt) prefer metallic iron, and atmophile elements (N, the noble gases) are concentrated in the atmosphere. A carbonate phase is not one of Goldschmidt's categories.

Q: Re and Os elements dominantly possesses which of the following geochemical character ?

Re and Os are dominantly siderophile.Osmium is one of the platinum-group elements and, like rhenium, has a strong affinity for metallic iron. During core formation both were strongly drawn into the core, so the silicate mantle and crust are very poor in them. This siderophile behaviour, with Re more incompatible than Os during mantle melting, is what makes the Re-Os isotope system useful for dating sulphides and tracing mantle and core processes.Both also show chalcophile tendencies in sulphide-rich systems, but their dominant character is siderophile. They are not lithophile elements, which concentrate in silicates. 'Immobile' describes behaviour during alteration, not a Goldschmidt class.

Elements that form ions with higher charge than the +2 found for the Mg⁺² Fe⁺² and Ca⁺² present in the octahedral sites in mafic and ultramafic rock forming minerals and are larger in size than the tetrahedral Si⁴⁺ and Al³⁺ sites in silicate minerals are termed as :

A.high field strength elements
B.Large ion lithophile elements
C.Transition metals
D.Heavy Rane Earth elements

Exam Year(s)

MH SET - 2018, SET Exam - 2018,

Answer: A

They are the high field strength elements (HFSE).

HFSE such as Zr, Hf, Nb, Ta and Ti form small ions with high charge (+3 to +5 and more), so their ratio of charge to radius, the field strength, is high. Their charge is too great for the octahedral sites occupied by Mg²⁺, Fe²⁺ and Ca²⁺, and they are too big for the tetrahedral sites of Si and Al, so they behave as incompatible elements.

Large ion lithophile elements (K, Rb, Cs, Sr, Ba) are incompatible for the opposite reason: large ions with low charge. Transition metals such as Ni and Cr fit readily into octahedral sites, and heavy rare earth elements are a separate group defined by atomic number.

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Lithophile elements show affinity for :

A.Sulphide phase
B.Atmosphere
C.Carbonate phase
D.Silicate phase

Exam Year(s)

MH SET - 2020, SET Exam - 2020,

Answer: D

Lithophile elements show affinity for the silicate phase.

In Goldschmidt's geochemical classification, lithophile ('rock-loving') elements, such as Na, K, Ca, Mg, Al, Si, the rare earths and U, combine readily with oxygen and concentrate in silicate minerals of the crust and mantle.

Chalcophile elements (Cu, Zn, Pb) prefer the sulphide phase, siderophile elements (Fe, Ni, Pt) prefer metallic iron, and atmophile elements (N, the noble gases) are concentrated in the atmosphere. A carbonate phase is not one of Goldschmidt's categories.

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Re and Os elements dominantly possesses which of the following geochemical character ?

A.Chalcophile
B.Siderophile
C.Lithophile
D.Immobile

Exam Year(s)

MH SET - 2025, SET Exam - 2025,

Answer: B

Re and Os are dominantly siderophile.

Osmium is one of the platinum-group elements and, like rhenium, has a strong affinity for metallic iron. During core formation both were strongly drawn into the core, so the silicate mantle and crust are very poor in them. This siderophile behaviour, with Re more incompatible than Os during mantle melting, is what makes the Re-Os isotope system useful for dating sulphides and tracing mantle and core processes.

Both also show chalcophile tendencies in sulphide-rich systems, but their dominant character is siderophile. They are not lithophile elements, which concentrate in silicates. 'Immobile' describes behaviour during alteration, not a Goldschmidt class.

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Geochemical Classification of Elements Questions and Answers

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