Related Clues:

• Bringer of bad luck, in legend
• Shade of gray
• Australian gem
• Libra's stone
• It's less dense than quartz
• Iridescent mineral
• Certain birthstone
• Birthstone for 31-Across
• Gem with a play of colors
• Down Under gemstone
• Stone from Down Under
• Gemstone
• Hyalite
• Fire ___ (gem)
• Milky stone