What is a syenite in geology ?

Syenite : definition

Streckeisen diagrams (or QAPF diagrams) - Classification of plutonic and volcanic rocks
A syenite is a light-coloured (whitish to pinkish) granular magmatic rock, made up of more than 60% of alkaline feldspars (orthose, microcline, anorthose, sometimes albite) accompanied by biotite and amphibole (hornblende), a small amount (less than 5%) of quartz or feldspathoid is allowed.

The alkaline varieties contain amphiboles and sodium pyroxenes (aegirine, riebeckite...). Mineralogical variations define the varieties of syenites : larvikite, pulaskite, normarkite...

Syenite is a fairly rare rock that forms small massifs or differentiations within granite massifs. Its volcanic equivalent is trachyte, a rock well represented in Auvergne volcanism : sancyites, domites, doreite, etc... are trachytes.
Larvikite en cabochon
Larvikite from Norway
Syenite à hornblende des USA
Hornblende syenite from USA

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

Google Analytics

Google Analytics is a service used on our website that tracks, reports traffic and measures how users interact with our website content in order for us to improve it and provide better services.

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