On a flattish disk of asteroidal rock a mile across, engineers of the past generation had raised a tower of metal rings.

Pulverized chunks of asteroidal rock were ruthlessly liquefied here, all their minor elements driven out to be collected by the mass separators, purified into the metals and minerals that were building the human race's expanding civilization.

Rugged and highly individualistic, Belters make their living by mining the ores from the asteroidal rocks.

A door opened to their right and they found themselves walking down a long corridor carved from the naked asteroidal rock.

Matter of fact," he said, "why can't you put three or four of your armed ships together, armor them with asteroidal rock, and keep them on station at a decent distance around Vesta?

Both the escorts were studded with asteroidal rock, armor to absorb and deflect laser beams.

There were six ferries in the bay-half a year's output from the Martin Kurster Memorial Shipyard, consuming a costly stream of crushed asteroidal rock.

Were Earth's resources to be spread indiscriminately among the asteroidal rocks?

A sliver of asteroidal rock sheared it off clean to the shoulder.

Further investigation revealed that the ring is not gas nor dust, nor even asteroidal rock, but a solid band of considerable tensile strength.