Primary rocks are the first type of rock to form from the Earth’s mantle and are also known as igneous rocks. They are formed when magma (molten rock) cools and solidifies. Primary rocks can be further classified into three main categories:

1. Intrusive Rocks: These rocks form when magma cools and solidifies beneath the Earth’s surface, resulting in a coarse-grained texture. Examples include:
   • Granite: A common intrusive rock that forms from the slow cooling of magma deep within the Earth’s crust.
   • Gabbro: A dark-colored intrusive rock that forms from the slow cooling of magma.
2. Extrusive Rocks: These rocks form when magma erupts onto the Earth’s surface as lava and cools rapidly, resulting in a fine-grained texture. Examples include:
   • Basalt: A common extrusive rock that forms from the rapid cooling of lava.
   • Andesite: A fine-grained extrusive rock that forms from the rapid cooling of lava.
3. Pyroclastic Rocks: These rocks form when magma is explosively ejected into the air and cools rapidly, resulting in a glassy or fragmented texture. Examples include:
   • Pumice: A lightweight, porous pyroclastic rock that forms from the rapid cooling of volcanic ash.
   • Ignimbrite: A type of pyroclastic rock that forms from the rapid cooling of hot, ash-rich clouds.

Other characteristics of primary rocks include:

• Mineral composition: Primary rocks are composed primarily of minerals such as quartz, feldspar, and mica.
• Texture: Primary rocks can have a range of textures, including coarse-grained, fine-grained, and glassy.
• Color: Primary rocks can range in color from dark gray to light-colored, depending on their mineral composition and texture.