They stopped for the evening just within the mouth of one of the chasm’s tributaries. Humbolt went out to get a drink where a trickle of water ran through the sand and as he knelt down he saw the flash of something red under him, almost buried in the sand.

He lifted it out. It was a stone half the size of his hand; darkly translucent and glowing in the light of the setting sun like blood.

It was a ruby.

He looked, and saw another gleam a little farther up the stream. It was another ruby, almost as large as the first one. Near it was a flawless blue sapphire. Scattered here and there were smaller rubies and sapphires, down to the size of grains of sand.

He went farther upstream and saw specimens of still another stone. They were colorless but burning with internal fires. He rubbed one of them hard across the ruby he still carried and there was a gritting sound as it cut a deep scratch in the ruby.