English: Magnesiocarbonatite (7.4 cm across along the bottom part of the sample) from the Verity-Paradise Carbonatite Complex of British Columbia, Canada.

Magnesiocarbonatites have a significant component of dolomite (CaMg(CO3)2 - calcium magnesium carbonate). The rock shown here is a magnesiocarbonatite from southwestern Canada. This is from the Verity Carbonatite, a 15 to 31 meter thick intrusive sill forming part of the Omineca Alkaline Province’s central carbonatite belt. Rocks from the Verity have also been called beforsites (= medium- to finely-crystalline Mg-rich carbonatites) and rauhaugites (coarsely-crystalline Mg-rich carbonatites). The “beforsite” and “rauhaugite” rock names have been replaced by the more meaningful term “magnesiocarbonatite”.

This rock is dominated by calcite and dolomite (the whitish to light gray portions of the rock), plus magnetite (black) and apatite (see rounded whitish spots in the middle portions of the rock). The rock is now somewhat foliated, the result of Mesozoic metamorphism, but the alteration appears not to have changed the mineralogy. It also contains vermiculitized phlogopite mica, zircon, and pyrochlore. Mining companies have expressed interest in the rocks from this general area, principally for the niobium (Nb) and tantalum (Ta) content of the pyrochlore.

Locality: Mt. Lempriere, between Rt. 5 and Kinbasket Lake Reservoir, Monasheee Mountains, southeastern British Columbia, southwestern Canada. Vicinity of 52º 23’ 26” N, 118º 58’ 40” W.