"Blockchain is great, but it can't solve everything. Take conflict minerals.", 23 April 2019.

...many are suggesting [blockchain] could be the answer to conflict minerals...Strengthening the traceability of goods such as tin, wolframite, coltan and gold would help ensure their extraction is not fuelling conflict and relying on child labour. Enhancing transparency in mineral supply chains is understandably at core of the OECD 2019 Forum on responsible mineral supply chains being held this week...Anglo American Plc plans to track gemstones using the technology, while others intend to trace gold from small-scale mines. Rwanda...already launched a blockchain-based system to trace tantalum in three mines and a smelter in 2018. The government wants to disprove allegations that its commodities are blended with smuggled conflict minerals from neighbouring DRC...

The tantalum blockchain system relies on identified and trusted participants performing their allocated role on the journey. But the key weakness in the system is the point at which the ore is first registered...Facial recognition guarantees that the persons at this initial point...are known. However, it does not guarantee that the ore registered genuinely originates from legitimate sources. The individuals selling and registering the products can still decide to collude for a kick-back and attach the wrong tag to a batch of tantalum from a small-scale mine controlled by armed groups...Neither facial scanning nor GPS recording guarantees where the authenticated seller got the tantalum from at this crucial first step...In fact, blockchain represents no progress over existing bag-and-tag traceability systems developed for the same minerals....Other approaches such as analytical fingerprinting of tantalum or adding markers at the molecular level in oil and gas engage with the raw material directly. They can – in contrast to blockchain – provide the proof of origin. But they are available only for some minerals due to technological limitations...