Societe Miniere de Bisunzu, the Democratic Republic of the Congo's biggest coltan miner, will end its ITSCI certification due to rising costs, Reuters reported Jan. 7, citing the Communications Director Philippe Stuyck.

Coltan is an ore containing niobium and tantalum and is used in technological products such as mobile phones and laptops.

The ITSCI scheme is a responsible supply-chain initiative many companies use to ensure the minerals they use are free from conflict, child labor and human rights abuses.

Many mining companies are complaining that the costs of the certification are becoming an increasing burden, but they have been reluctant to pull out over concerns that it will be hard to sell their minerals without the certification, according to the report.

Jean Malic Kalima, the chairman of the Rwanda Mining Association, estimated certification costs at US$130/t to US$180/t, based on the mineral involved.