Using filters on the rover's Mast camera (Mastcam) and an instrument which shoots neutrons into the ground to probe for hydrogen, researchers have detected more hydrated minerals near the clay-bearing rock than at locations Curiosity visited earlier in its mission.

BBC: Curiosity breaks rock to reveal dazzling white interior

First is a core of rock, then clay and lastly soil, topped with grass seed that will withstand being walked on.

BBC: Northumberlandia: The naked lady of Cramlington

The scythe's smaller cousin, the sickle, dates back more than 5, 000 years, and was initially made out of rock or baked clay.

FORBES

Sediment: particles of rock covering a size range from clay to boulders.

UNESCO: L O S S A R Y

If it can happen on an island of rock, it would be disastrous if it happened in our clay basin.

BBC: Thames Barrier engineer says second defence needed

Dr Hazen and his team speculate from meteorite and early rock studies that several hundred mineral species, including zircon, quartz, clay and halite salt crystals, formed during this early period of mineral evolution.

ECONOMIST: Minerals