Lamproite

Lamproite (from Greek λαμπρός, shiny ') is a dark gray porphyritic rock, which belongs to the class of igneous rocks. By its mineralogical composition, several sub- species can be distinguished. Lamproite occurs only in a few areas of the Earth, forming volcanic deposits ( Pyroklastite ) or solidified at shallow depths subvolcanic volcanic vents. Closely related rocks are kimberlite and lamprophyre Orangeit.

Composition

Characteristic Lamproite is a significant proportion of most titanium-containing phlogopite ( mica mineral ), followed by the name of the stone decreases. Other main ingredients are leucite, richterite, olivine, diopside and sanidine. However, the mineralogical composition varies within very wide limits, so that each of these minerals can outweigh modal and others may be missing. In lesser amounts often occur Priderit, Wadeit, apatite, perovskite, chromite, enstatite, and magnetite. In some Lamproiten is also mentioned diamond.

Chemically, lamproite to about 45-55 weight percent of silicon dioxide. He also has a high potassium content and therefore belongs to the group of alkaline rocks. It is characterized by a very high ratio of potassium to sodium. The contents of iron, calcium and titanium can be significant.

Economic Importance

Diamond -containing Lamproite are an important source of diamond production. Occurrence diamanthaltiger Lamproite example, Argyle (Kimberley, Australia), Prairie Creek ( Arkansas), Majhgawan (India) and Bobi Segeula (Ivory Coast).