"But why in the devil's name should this metal mountain alone on the whole planet remain non-radioactive?’ cried Gunner Welk, his massive face incredulous. “It doesn't make sense."
"I think I understand that,” Sual Av said keenly, his green eyes gleaming. “I took a good look at the black metal of this mountain as we climbed up over it. It's a solid mass of asterium."
"Asterium?” Thorn echoed. “That queer element they've found in meteors from outer space?"
Sual Av's bald head bobbed eagerly. “Yes, the element whose discovery forced them to revise the periodic table — the most inert element ever discovered. It's completely resistant to radioactive action, they found.""
"But asterium was supposed to be an element foreign to our solar system, one formed somehow in far-off giant stars!” cried Gunner. “How the devil would there happen to he a solid mountain of the stuff here on Erebus?"
"This mountain of asterium was not always native to Erebus, if my guess is right,” retorted the Venusian. “This mountain came here from outer space. It's a gigantic meteorite of almost solid asterium that fell here on Erebus in some past age."
"By heaven, I believe Sual's right!” Gunner exclaimed excitedly. “That would explain the peculiar domed shape of the mountain. It's roughly spherical, but half of it is buried."
Old Stilicho Keene had listened, only half-understanding. Now he ventured an anxious question to Thorn.
"If it's doom to step off this mountain as that there Saturnian says, then how could Cheerly and his men and Lana dare to leave here on foot to search for the radite?"
"If my guess is right, they had some sort of protection against the radioactive emanations out there,” Thorn clipped. He turned to the Saturnian officer. “What about it?"