TIL Nauru is the most obese country in the world, it's estimated that 94.5% of Nauruans are overweight or obese
TIL Nauru is the most obese country in the world, it's estimated that 94.5% of Nauruans are overweight or obese
Obesity in Nauru - Wikipedia

Ninety percent??? Ninety!?!?
Basically at some point in the 70s they sold their rights to Australia, who came in and destroyed the island. They were, for a bit, the wealthiest people in the world per capita but the money ran out fairly quickly.
They are basically the metaphor for modern human civilisation.
i'm guessing "phosphate deposits" is a very roundabout way to say "guano".
More than likely it's buildups of marine life deposits considering it's an island. Phosphates are usually mined from naturally occurring porous stones that phosphorus has diffused through over a long period of time.
Guano has some phosphates in it, but is usually sought after for its high nitrogen content, and is typically located near coastal areas or caves as opposed to remote islands.
These were mineral deposits.