During the geological prospecting works conducted in 2013 on Bangka Island (Indonesia), high monazite content was identified in the wastes produced during processing of cassiterite deposits. Monazite, among 250 known minerals containing REE , is one of the most important minerals as primary source of REE .The monazite content in this waste is up to 90.60%. The phase composition of the investigated tailing proves that the sources of minerals accompanying the placer sediments tin mineralization are granitoids. The tailing is composed of numerous ore minerals, including monazite, xenotime, zircon, cassiterite, malayaite, struverite, aeschynite-(Y), ilmenite, rutile, pseudorutile and anatase. Monazite grains belong to the group of cerium monazite. Its grains are characterized by high content of Ce2O3 27.12–33.50 w t.%, La2O3 up to 15.46 w t.%, Nd2O3 up to 12.87%. The total REE 2O3 + Y content ranges from 58.18 to 65.90 wt.%. Monazite grains observations (SEM -BSE) revealed the presence of porous zones filled with fine phases of minerals with U and Th content. The radiation intensity of 232Th is ATh = 340 ± 10 Bq and 238AU = 114 ± 2 Bq. High content of monazite and other REE minerals indicates that tailing is a very rich, potential source of REE s, although the presence of radioactive elements at the moment is a technological obstacle in their processing and use. The utilization of monazite bearing waste in the Indonesian Islands can be an important factor for development and economic activation of this region and an example of the good practice of circular economy rules.

Phosphate rocks and elemental phosphorus are considered to be critical raw materials mainly because of such parameters as the growing prices of phosphate fertilizers, the high concentration of producers limited to several countries in the world, the exceptional significance of phosphorus in agriculture and the inability to substitute it.
In Poland 100% of the demand phosphate rocks relies on import. The expansion and mining of the nation’s own resource base may be an alternative to import and a way to provide safety of supplies. Historically, phosphorites from the northern margin of the Holy Cross Mountains were extracted using the underground method, which was abandoned in the beginning of the 1970s due to the unprofitability of extraction. However, in eastern and south-eastern Poland, phosphorite concretions of the Eocene age occur at shallow depths, which can have local significance as mineral deposits and might be extracted in open-pit mines. The economics of mining in shallow opencasts do not require such stringent limiting parameters for phosphate deposits as those currently valid, which were established for underground mining conditions.
In this publication, the authors analyzed contemporary conditions for a cost-effective phosphorite deposit, including the price fluctuations of phosphate rock, a review of threshold parameters of deposits for phosphorite projects in the world, and the economics of open-pit ore extraction, where an aggregate mine with mixed extraction (partially from below the water table) was adopted as a point of reference.
As a result, new threshold parameters defining an ore deposit and its boundaries are proposed for Eocene phosphorites in Poland.