* Quartz (SiO2): Quartz is a very common mineral found in many igneous and metamorphic rocks. It's resistant to weathering and can be found in a variety of colors.
* Feldspar (various compositions): Feldspars are a group of minerals that are also abundant in igneous and metamorphic rocks. They can be found in different forms, including orthoclase, plagioclase, and others.
* Biotite (K(Mg,Fe)3AlSi3O10(OH)2): Biotite is a black mica mineral often found in metamorphic rocks like gneiss and hornfels.
* Muscovite (KAl2(AlSi3O10)(OH)2): Muscovite is a white or silver mica mineral that can be found in metamorphic rocks.
Here's why these minerals are common in all of these rocks:
* Granite: Granite is an igneous rock that is typically composed of quartz, feldspar, and mica.
* Andesite: Andesite is also an igneous rock, often with a similar mineral composition to granite, although it tends to have more plagioclase feldspar and less quartz.
* Gneiss: Gneiss is a metamorphic rock that forms from the alteration of other rocks, often granite or andesite. The heat and pressure of metamorphism can recrystallize minerals, resulting in a layered or banded appearance.
* Hornfels: Hornfels is a metamorphic rock that is formed by the contact metamorphism of other rocks. It often has a fine-grained texture and may contain a variety of minerals, including those mentioned above.
Remember:
* The specific mineral composition of each rock type can vary depending on the original rock and the conditions of its formation.
* Some other minerals may also be present in these rocks depending on their origin and metamorphic history.