We introduce a modification to the current IUGS classification system for igneous rocks to include ultramafic lamprophyres, which are currently entirely omitted. This is done by including a new step ...

The Journal of Geology, Vol. 85, No. 1 (Jan., 1977), pp. 49-61 (13 pages) This classification of spinel facies ultramafic xenoliths is based on thin-section criteria, and encompasses rocks of all ...