Related Clues:

• Fire or water, e.g.
• It's found in a table
• Essential part
• Mercury, but not Mars
• Constituent
• Component
• Natural surroundings
• Hydrogen, e.g.
• Gold or silver
• Copper or nickel
• Normal habitat
• Tin or titanium
• Tin or tungsten
• Neon or nobelium, e.g.
• See 39 Across