Question

The chemical formula of willemite is:
A) ${\text{ZnS}}$
B) ${\text{ZnC}}{{\text{O}}_{\text{3}}}$
C) ${\text{ZnO}}$
D) ${\text{Z}}{{\text{n}}_{\text{2}}}{\text{Si}}{{\text{O}}_{\text{4}}}$

Answer 1

To solve this we must know that willemite is a mineral and is a minor ore of zinc. Willemite occurs in the regions of Arizona. Willemite is formed due to alteration of sphalerite ores and it is associated with limestone. Willemite is also found in marbles.

Complete step-by-step answer:
${\text{ZnS}}$ is zinc sulphide. Zinc sulphide is also known as zinc blende or wurtzite. Thus, option (A) is not correct.

${\text{ZnC}}{{\text{O}}_{\text{3}}}$ is zinc carbonate. Zinc carbonate is also known as smithsonite or turkey fat or zinc spar. Thus, option (B) is not correct.

${\text{ZnO}}$ is zinc oxide. Zinc oxide is also known as calamine or Chinese white. Thus, option (C) is not correct.

${\text{Z}}{{\text{n}}_{\text{2}}}{\text{Si}}{{\text{O}}_{\text{4}}}$ is zinc silicate. Zinc silicate is also known as willemite. We know that willemite is a mineral and is a minor ore of zinc. Willemite occurs in the regions of Arizona. Willemite is formed due to alteration of sphalerite ores and it is associated with limestone. Willemite is also found in marbles.

Willemite occurs with red zincite i.e. zinc oxide and franklinite which is an iron rich mineral. Willemite is a silicate mineral and an ore of zinc having chemical formula ${\text{Z}}{{\text{n}}_{\text{2}}}{\text{Si}}{{\text{O}}_{\text{4}}}$.
Thus, the chemical formula of willemite is ${\text{Z}}{{\text{n}}_{\text{2}}}{\text{Si}}{{\text{O}}_{\text{4}}}$.

Thus, the correct option is (D) ${\text{Z}}{{\text{n}}_{\text{2}}}{\text{Si}}{{\text{O}}_{\text{4}}}$.

Note: Willemite is highly fluorescent under ultraviolet light. In daylight, willemite occurs in a wide variety of colours. It is brown in colour when found as a solid mass and appears apple green when found in gemmy mass. Sometimes willemite also appears as burgundy-red or pink in colour.