rocks

 Rocks are solid aggregates of minerals, mineraloids, or organic materials that make up the Earth's crust. They form through various geological processes such as cooling and solidification of molten lava or magma, precipitation of minerals from water solutions, and consolidation of sediment particles.

There are three main types of rocks based on their formation processes:

1. **Igneous Rocks**: These rocks form from the solidification of molten material, either magma (below the surface) or lava (on the surface). 

Igneous rocks can be further classified into two main types:

   - **Intrusive Igneous Rocks**: Formed from magma that cools and solidifies below the Earth's surface. Examples include granite and diorite.

   - **Extrusive Igneous Rocks**: Formed from lava that cools and solidifies on the Earth's surface. Examples include basalt

 and 

obsidian.

 

2. **Sedimentary Rocks**: These rocks form from the accumulation and cementation of sediment particles, organic matter, or chemical precipitates. Sedimentary rocks are typically formed in layers over long periods of time.

They can be further classified into:

   - **Clastic Sedimentary Rocks**: Formed from the accumulation of fragments of other rocks. Examples include sandstone, shale, and conglomerate.

   - **Chemical Sedimentary Rocks**: Formed from the precipitation of minerals from water solutions. Examples include limestone and rock salt.

   - **Organic Sedimentary Rocks**: Formed from the accumulation and compression of organic matter, such as plant remains. Examples include coal and some types of limestone.

3. **Metamorphic Rocks**: These rocks form from the alteration of existing rocks due to heat, pressure, and/or chemically active fluids deep within the Earth's crust. Metamorphic rocks are often characterized by foliation, which is the alignment of mineral grains in parallel layers. Examples include marble (from limestone), slate (from shale), and gneiss (from granite).

These three types of rocks are interconnected through the rock cycle, which describes the processes by which rocks are continuously transformed from one type to another over geological time scales.