the switch, his thumb found the discharger button and sent out a radio
impulse; the red rag vanished in an upsurge of smoke and dust that mounted
out of the gorge and turned to copper when the sunlight touched it. The
big manipulator, weightless on contragravity, rocked gently; falling
debris pelted the trees and splashed in the little stream.

He waited till the machine stabilized, then glided it down to where he had
ripped a gash in the cliff with the charge of cataclysmite. Good shot:
brought down a lot of sandstone, cracked the vein of flint and hadn't
thrown it around too much. A lot of big slabs were loose. Extending the
forward claw-arms, he pulled and tugged, and then used the underside
grapples to pick up a chunk and drop it on the flat ground between the
cliff and the stream. He dropped another chunk on it, breaking both of
them, and then another and another, until he had all he could work over
the rest of the day. Then he set down, got the toolbox and the
long-handled contragravity lifter, and climbed to the ground where he
opened the box, put on gloves and an eyescreen and got out a microray
scanner and a vibrohammer.

The first chunk he cracked off had nothing in it; the scanner gave the
uninterrupted pattern of homogenous structure. Picking it up with the
lifter, he swung it and threw it into the stream. On the fifteenth chunk,
he got an interruption pattern that told him that a sunstone--or
something, probably something--was inside.

Some fifty million years ago, when the planet that had been called
Zarathustra (for the last twenty-five million) was young, there had
existed a marine life form, something like a jellyfish. As these died,
they had sunk into the sea-bottom ooze; sand had covered the ooze and
pressed it tighter and tighter, until it had become glassy flint, and the