That is a necessary but not a sufficient condition, as the type of rock involved, called carbonaceous chondrite, is found in other asteroids, too.

ECONOMIST: Asteroid impacts

Yellowknife was chosen as a destination because it represents a different type of rock terrain from the one on which Curiosity landed in August and on which it has done most of its driving.

BBC: Mars rover finally looks set to drill

The label featured a rather ugly brown rock. (Silex is the type of soil found in the Dagueneau vineyards.) "It is kind of ugly, " I admitted.

WSJ: Bryan Ferry, Drinking Wine With Lettie Teague

As Music Producer, he also recorded every type of local performer - from big bands to rock bands - Mike Harding to Jon Anderson.

BBC: Presenter profile: Gerald Jackson

It says the flash of light comes not from any type of combustion -- as we typically think of explosions -- but rather by the glowing molten rock at the impact site.

CNN: Bright explosion on moon visible from Earth, NASA says