Basanite is a black volcanic rock with a microlitic texture and often porphyritic, similar in appearance to basalt
, consisting of calcium plagioclase
(labrador most often), feldspathoid, augite, brown hornblende, olivine
and sometimes biotite. The presence of olivine differentiates basanite (which contains it) from tephrite
(which does not contain it).
The nature of the feldspathoid makes it possible to distinguish varieties : the usual basanite is with dominant nepheline, analcime
and hauyne ; the ankaratrite is nepheline and pyroxene ; limburgite with augite, olivine
. Basanite forms flows generally associated with olivine basalts.