Question

Precious stone, such as gemstones, are products of
a. Volcanic rocks
b. Sedimentary rocks
c. Metamorphic rocks
d. Igneous rocks

Answer 1

Hint: Precious stones, such as gemstones, are products of rocks formed by cooling and solidification. Gemstones are a part of mineral crystals. Most of the gemstones are hard but the ones that are used to make jewelry are soft, lustrous and have aesthetic value.

Complete answer:
Igneous rocks: It is also called magmatic rock. It is formed when the lava or magma gets cooled down and solidifies. Igneous rocks may form crystalline rocks or natural glasses.
Gemstones: These are commonly made from minerals or other materials like jet, amber, or rocks. Most of them are formed below the earth. When minerals react with water present below the earth's surface it gets dissolved and when the cooling occurs. It leads to the formation of a gemstone. The gemstones are of high value. Some of the examples are diamond, sapphire, ruby, emerald, etc.
Also,
Volcanic rocks: These are the rocks that are formed due to the eruption of the lava from the volcano. These are the most common types of rock found on the earth's surface. They also contain some of the common minerals.
Sedimentary rocks: These are formed due to the deposition or sedimentation of the minerals, small particles, or other organic matter on the earth surface or the floor of oceans.
Metamorphic rocks: are formed by the modifications in the existing rocks through a process called metamorphism. The factors of metamorphism may be temperature or pressure.

Hence, the correct answer is option (D).

Note: The gemstones that formed are then cut and polished to make jewelry or other products. They are of high value as they are rare. Gemstones are classified into various types like emerald, corundum, aquamarine, etc. Those who identify gemstones are called gemologists.