Question

Which one of the following is the chief ore of copper?
A. galena
B. copper pyrite
C. siderite
D. All of the above

Answer 1

Hint: Chief ore means the ore from which the element is generally obtained. Check all the options. In the crystal structure of the chief ore, each metal ion is tetrahedrally connected to four sulphur anions. The sulphur is bonded to the copper atoms as well as the iron atoms.

Complete step by step answer:
Let us understand all the options one by one, to find the chief ore.
A. Galena: It is the most important ore of lead. This ore is also called lead glance. It is the natural form of lead (II) sulphide $\left( \text{PbS} \right)$. It is an important source of silver. It has a silvery colour. It is the principal ore of lead.

B. Copper pyrite: Copper pyrite is also known as chalcopyrite. Chalcopyrite is derived from the word ‘chalkos’, which means copper and ‘pyrites’ which means striking fire. The chemical formula of this pyrite is $\text{CuFe}{{\text{S}}_{2}}$. It is the most important ore of copper.

C. Siderite: This ore is not an ore of copper. Siderite is composed of iron (II) and has the formula $\text{FeC}{{\text{O}}_{3}}$. It is derived from the word sideros which means ‘iron’. It is an iron mineral and contains $48%$ iron and contains no sulphur.
So, the correct answer is “Option B”.

Additional Information:
Copper metal can be extracted from a mixture of silica sand and copper pyrite through open air roasting. The reactions involved are $2\text{CuFe}{{\text{S}}_{2}}\left( \text{l} \right)+5{{\text{O}}_{2}}\left( \text{g} \right)+2\text{Si}{{\text{O}}_{2}}\left( \text{g} \right)\rightleftharpoons 2\text{Cu}\left( \text{l} \right)+4\text{S}{{\text{O}}_{2}}\left( \text{g} \right)+2\text{FeSi}{{\text{O}}_{3}}\left( \text{l} \right)$.

Note: Copper pyrite is not confused to be with pyrite and gold as all the three minerals have a yellowish colour and a metallic lustre. The important characteristics that help to distinguish these minerals are hardness and streak. Copper pyrite can be scratched with a knife, whereas pyrite cannot be scratched by a knife, so copper pyrite is much softer than pyrite.