What are hornfels in geology ?

Hornfels - Metamorphism

Metamorphic facies diagram
An hornfel is a rock of contact metamorphism of granitoids, usually very hard.

Its mineralogical composition varies according to the nature of the host rocks :

- pelitic rocks give micaceous hornfels with andalusite and cordierite, evolving into feldspathic hornfels
- marl-limestone rocks and calcareous pelites give calcic hornfels, called tactites, of variable mineralogical composition, usually rich in garnet, epidote and hornblende.
- carbonate rocks give skarns and marbles
- the other rocks evolve according to their original mineralogical composition (for example, for quartzose sandstones the hornfel ones will be quartzites).

The hornfels can give rise to exploitable concentrations of metals (gold, copper, tungsten, etc...) or industrial minerals (andalusite from Glomel in Côtes-d'Armor, France for example).

ReCaptcha

This service is used to secure web forms of our website and required if you want to contact us. By accepting it you agree to Google's privacy policy: https://policies.google.com/privacy

Facebook

Our website allows you to like or share its content on Facebook social network. By activating and using it you agree to Facebook's privacy policy: https://www.facebook.com/policy/cookies/

YouTube

Integrated videos provided by YouTube are used on our website. By accepting to watch them you agree to Google's privacy policy: https://policies.google.com/privacy

Twitter

Integrated tweets and share services of Twitter are used on our website. By accepting and using these you agree to Twitter's privacy policy: https://help.twitter.com/en/rules-and-policies/twitter-cookies

PInterest

Our website allows you to share its content on PInterest social network. By activating and using it you agree to PInterest's privacy policy: https://policy.pinterest.com/en/privacy-policy/