Among the cases mentioned at the time was Australia's Lynas Rare Earths, curiously reconverted from gold mining to rare earths. In addition to its rather troubled history, the company operated a deposit that was difficult to evaluate and a refining infrastructure in Malaysia exposed to multiple ecological, economic and geopolitical risks.

Generously financed by the capital markets since its inception, Lynas accumulated a number of suspect characteristics. These included an ultra-promotional management team with no proven track record in the mining industry - who were quick to offload their shares in the company - and, on paper, an economic performance to be true.

Yesterday, the Australian company published annual results that reinforce these doubts. At the top of the press release is a triumphant book profit of AUD $311 million, but a clever vagueness is maintained over negative cash flows and a surprisingly low depreciation and amortization charge.

Moreover, sales were down despite record production - due to falling oil prices - while the company carried out its umpteenth capital increase this year to develop its infrastructure in Malaysia.

The MarketScreener editorial team has devoted numerous articles to the rare earths sector - rare in name only, since they are abundant in the earth's crust, but require highly complex and polluting refining infrastructures to exploit.