1. Formed by solidification of molten magma on cooling.

1. Formed by the consolidation of sediments.

1. Formed by subsequent transformation igneous and sedimentary rocks.

2. It may be called primary rocks because it formed first.

2. It is derived from the breaking down of primary rocks.

2. It is derived from the breaking down of primary and secondary rocks.

3. Igneous rocks consist mainly of primary minerals of which quartz, feldspar’s, amphiboles, pyroxenes, and mica are the most common.

 

3. Sedimentary rocks consist mainly of secondary minerals together with some qualities of primary minerals, such as limestone, sandstone, siltstone, shale, calcareous sandstone, arenaceous limestone, etc.

3. Metamorphic rocks consist of mainly granite, shales, limestone, sandstone, etc.

4. No action of water, glacier, and wind is taken place.

4. The action of water, glacier, and wind is taken place.

4. Influenced by heat, pressure, and gasses.

5. They have no layer so they called unstratified rocks.

5. They have layers so they called stratified rocks.

5. They may be layered or no layered.

6. These rocks are often shiny and glossy.

6. These rocks are soft looking and can contain fossils.

6. These rocks are hard and often contain crystals.

7. Example: Granite, gabbro, basalt, etc.

7. Example: Sandstone, siltstone, shale, etc.

7. Example: Marble, slate, gneiss, quartzite, etc.