Answer: $1 \to c;\quad 2 \to a; \quad 3\to d; \quad 4 \to b$
Factual Question about Copper Ores.
1. Cuprite is an oxide mineral composed of copper(I) oxide Cu$_2$O, and is a minor ore of copper.
2. Chalcocite, copper(I) sulfide (Cu$_2$S), is an important copper ore mineral. It is opaque, being colored dark-gray to black with a metallic luster
3. Chalcopyrite is a copper iron sulfide mineral that crystallizes in the tetragonal system. It has the chemical composition CuFeS$_2$.
4. Malachite is a copper carbonate hydroxide mineral, with the formula Cu$_2$CO$_3$(OH)$_2$. This opaque, green banded mineral crystallizes in the monoclinic crystal system, and most often forms botryoidal, fibrous, or stalagmitic masses