Here's a breakdown of the common minerals found in amphibolite:
Essential minerals:
* Amphiboles: These are the defining feature of the rock. Common amphiboles include hornblende, actinolite, and tremolite. They form long, prismatic crystals and often have a dark green to black color.
Common accessory minerals:
* Plagioclase feldspar: This is a common mineral in many metamorphic rocks, and it can range in color from white to gray.
* Quartz: This is a hard, colorless mineral that is also common in metamorphic rocks.
* Biotite: This is a dark mica mineral that can be black or brown.
* Garnet: This is a red or green mineral that can be found in some amphibolites.
* Epidote: This is a green mineral that can be found in some amphibolites.
Other possible minerals:
* Pyroxene: This is a common mineral in some amphibolites.
* Sphene: This is a yellow-brown mineral that can be found in some amphibolites.
* Magnetite: This is a black, magnetic mineral that can be found in some amphibolites.
Key factors influencing mineral composition:
* Original rock type: The minerals present in the original rock will influence the minerals that form in the amphibolite.
* Temperature and pressure: These factors control which amphiboles form, and the presence of other minerals.
* Chemical composition of the original rock: This will also influence the minerals that form in the amphibolite.
Amphibolites can be very diverse in terms of their mineral composition, but the presence of amphibole is always the defining characteristic.
