"minerals"

The updated geochemical atlas was an outgrowth of another project. Geologists and surveyors were on a mission to find rare earth elements and minerals that could be strategically important to the country.

Horse manure is good for your compost bin, but no pet droppings

It was formed in a region of the mantle known as the transition zone, some 250 to 400 miles below the surface.

As Adam Frank has said over on the 13.7 blog, “Earth and Mars have been swapping spit (astrobiologically speaking) for eons … [and] it is entirely possible we were Earth’s first alien invasion.”