The so-called Rare earth metals include a total of 17 elements. However in many publication different number of REE is classified. The REE are ruther more common elements within the Earth Crust, compared to copper, lead, arsenic or molybdenum. Tullium and lutetium, which are the rarest representatives of this group, are more common than gold and platinum. A peculiar feature of lanthanides is the so-called "lanthanide contraction", i.e. the decreasing atomic and ionic radii with increasing atomic number. The latter group includes praseodymium oxide and neodymium. Rare earth metals are usually found in the form of carbonates, oxides, phosphates and silicates. Most of the rare earth reserves are located in China. There are supposed to be deposits of 44 million tons of rare earth oxide equivalent (REO). The leaders in this respect also include Vietnam, Brazil and Russia.

Earth metals and strategic metals can be sourced from mineral deposits, mineral/technological waste, and recycling. Earth metals and strategic metals are mined in very different quantity. Bayan Obo in China is a major known REE deposit. It is located in China. Carbonatites are classified as a major genetic type deposit of the REE Carbonatites: are defined as an accumulation of carbonate minerals genetically connected with ultramaphic-alkaline magmatic intrusions. Carbonatites are magmatic rocks containing minimum 50% of carbonate minerals like calcite, dolomite, ankerite and some K-carbonates.

Actually (2024), in Poland there is no REE mining, however several deposits have been recognized. Tajno massif occurs among the Precambrian rocks of the crystalline basement of north-eastern Poland. Tajno carbonatites are present in form of thin veins in ijolites and syenites and cementing volcanic pipe breccia. Tajno carbonatite occupies 5 km² area and is overlain by over 600 m of sedimentary rocks. Reserves are estimated for 246,6 mln tons of ore (Ryka, 1992. Geology of Tajno massif carbonatite). An average content of the RE2O is 0,37%. Tajno rocks are composed of more than 70 minerals. The most common mineral in Tajno carbonatite (except calcite and fluorite) is burbankite - (Na,Ca)₃(Sr, Ba, Ce)₃(CO₃)₅. Others REE minerals occuring in Tajno massif are: as follows; parisite - Ca(Ce,La)₂(CO₃)₃F₂; synchysite - Ca(Ce,Nd,Y,La)(CO₃)₃F₂; bastnäsite - (Ce,La,Y)CO₃F. In the pegmatite and IOCG types of deposits allanites are common minerals. In the Sin Quen deposit in Vietnam, two variety minerals from allanite group have been documented. The sum of REE in these minerals ranges between 13-16 wt.% and 20-23 wt.% Only the policies of some countries maintain China's dominance as the main producer of REE.