http://www.newsweek.com/ships-are-mysteriously-sinking-cargo-suddenly-liquefies-1096960

Ships carrying granular materials in their holds could be at risk of sinking. Getty Images Share Tech & Science Cargo EngineeringThink of a dangerous cargo and toxic waste or explosives might come to mind. But granular cargoes such as crushed ore and mineral sands are responsible for the loss of numerous ships every year. On average, ten “solid bulk cargo” carriers have been lost at sea each year for the last decade. 

Solid bulk cargoes – defined as granular materials loaded directly into a ship’s hold – can suddenly turn from a solid state into a liquid state, a process known as liquefaction. And this can be disastrous for any ship carrying them – and their crew.