felsite's Usage Examples:

It is worthy of note that the dykes and sheets of felsite are seldom pierced by the basalt dykes and are probably about the most recent of the intrusive rocks.

In the south of the island there are sills and dykes of felsite, quartz-porphyry, rhyolite, trachyte and pitchstone.

These are penetrated by intrusions of granitic and felsitic character; one of these masses in Papa Stour is a handsome pink felsite.

The orthoschists are white mica-schists produced by the shearing of acid rocks, such as felsite and porphyry.

The felsite sheets are well represented in Holy Island.

Igneous rocks are not extensively developed; in Wales they form an important feature and occur in considerable thickness; they are represented by lavas of olivine-diabase and by contemporaneous tuffs which are traversed by later granite and quartz felsite.

Tertiary-aged dolerite and felsite dikes occur throughout the area and have a strike of NW-SE.

In Arran there are pitchstone dikes, some of which are very completely vitreous, while others are changed to spherulitic felsites more or less silicified.

felsite dike immediately on the coast.