On: 'No-water' hydropower turns England's hills into g...

[gorlilla]

My first guess was some form of alginate.

[kortex → gorlilla]

Alginate is probably not as dense as a suspension of kaolin, and also being an ionic polymer, there's no need for a surfactant or dispersant to stabilize it. Also it is probably way more expensive.

[pfdietz → gorlilla]

An organic compound would not have the density.