Phonolite - Wolf Rock
 >View Microscope
 >View Object
Fact sheet
Description: 

This fine-grained porphyritic igneous rock comes from Wolf Rock, a tiny part of land that lies in the treacherous waters between the Isles of Scilly and Land's End. This island off the coast of Cornwall is best known for its granite lighthouse, built between 1861 and 1869, which covers most of the area above water. The phonolite was intruded around 130 million years ago and is one of a suite of alkaline intrusions of similar age.

The thin section illustrates the fine-grained igneous of groundmass of sanidine, nepheline and augite pyroxene. Phenocrysts are dominated by tablular sanidine, although there are rounded, embayed and sometimes altered nepheline phenocrysts also present (see rotation 1). Dark brown six sided euhedral nosean phenocrysts are also present and contain abundant inclusions. In places the nosean phenocrysts are partially altered to analcime.

In Place
In Time
infoImage: 
Location description: 
A small island between the Isles os Scilly and Lands End in Cornwall
Accuracy:
Location precision: 
Moderate
Timescale:
Timescale: 
Cretaceous
Ma = Millions of years ago
In Focus
Theme:

Theme:

What\
Type:
Type: 
igneous
What\
Category:

Category:

What\
Rock-forming minerals:

Rock forming mineral:

What\
Accessory minerals:

Accessory minerals:

What\