Explanation:
Igneous rocks are formed by melting and cooling of magma originated from volcanic process.
when molten rock (rock liquefied by intense heat and pressure) cools to a solid state. Lava is molten rock flowing out of fissures or vents at volcanic centres (when cooled they form rocks such as basalt, rhyolite, or obsidian)
These rocks are strong, crystalline and dark in colour.
