What is Lamprophyre?

A group of rocks of variable composition, characterized by being potassium-rich and strongly porphyritic in mafic minerals, typically biotite, amphibole, and pyroxene—any feldspar (whether alkali or plagioclase feldspar) is confined to the matrix. Accessory minerals include hornblende, calcite, titanite, and magnetite.

TEXTURE Medium-grained, this group of rocks is typically porphyritic. Both biotite and hornblende phenocrysts give the rocks a distinctive appearance.

ORIGIN Forms in minor intrusions and in dykes and sills. The rocks often show signs of hydrothermal alteration. They can be associated with a variety of other igneous rocks, such as granites, syenites, and diorites.

Group: IGNEOUS

Origin: Extrusive

Grain size: Medium

Crystal shape: Anhedral, Euhedral

Classification: Felsic to mafic

Occurrence: Dyke, Sill

Color: Medium