Rapakivi granite

The name has come to be used most frequently as a textural term where it implies plagioclase rims around orthoclase in plutonic (intrusive) rocks.

Rapakivi granites have formation ages from Archean to recent and are usually attributed to anorogenic tectonic settings.

[citation needed] Rapakivi granites are often found associated with intrusions of anorthosite, norite, charnockite and mangerite.

[7][note 1] Rapakivi is enriched in K, Rb, Pb, Nb, Ta, Zr, Hf, Zn, Ga, Sn, Th, U, F and rare earth elements, and poor in Ca, Mg, Al, P and Sr. Fe/Mg, K/Na and Rb/Sr ratios are high.

[17] In 1770, a rapakivi granite monolith boulder, the "Thunder Stone", was used as the pedestal for the Bronze Horseman statue in Saint Petersburg, Russia.

Eroded rapakivi granite in Finland
Rapakivi type wiborgite
Rapakivi type pyterlite