"Thank you." Richard accepted the list Wizard Inogaowa handed him and scanned it a few times. He quickly spotted several materials that had yet to be collected, each marked with an X.
More precisely, there were two that had not been found.
The first was called Rhenium Stone on the list. It was actually rhenium.
It was a silvery-white metal, very hard, wear-resistant, corrosion-resistant, and insoluble in Hydrochloric Acid and Hydrofluoric Acid. It had one outstanding trait: heat resistance. Its melting point was 3180°C, the third highest among metals, while its boiling point reached an astonishing 5627°C, the highest of all metals.
This metal also possessed a "Rhenium Effect." When made into an alloy, it could greatly improve the strength and plasticity of tungsten, molybdenum, and chromium. Adding a small amount of rhenium, 3% to 5%, could raise tungsten's recrystallization temperature by 300°C to 500°C. That was precisely why, after an Implosion-Type Nuclear Weapon ignited its high explosives, Rhenium-Tungsten Alloy could remain unaffected under high temperatures and pressures as it compressed the nuclear material.
The second was called Sweet Green Stone on the list. It was actually beryllium.
This was a gray metal, brittle at room temperature. Its elastic modulus was roughly 50% higher than that of steel, yet its density was relatively low, resulting in an extremely high speed of sound. Under standard temperature and pressure, sound traveled through it at approximately 12.9 km/s—under the same conditions, sound traveling through air only moved at a little over three hundred meters per second.
Of course, none of that was important. What mattered was that, apart from trace radioactive isotopes caused by cosmic rays, natural beryllium was almost entirely composed of beryllium-9 isotopes with a nuclear spin of 3/2. This gave it a relatively large cross-section for high-energy neutrons. For neutrons