1. optical illusion due to atmospheric conditions.   yield   patina   mirage   vent   Hint Half-n-half Clue   2. marsh or soft and wet land.   projectile   quagmire   residue   pigment   Half-n-half Clue   3. target or goal.   precipitant   objective   serendipity   metamorphosis   Half-n-half Clue   4. residue from smelting operation.   magnitude   patina   slag   whorl   Half-n-half Clue   5. layer of earth's crust or society.   stratum   iota   vertex   kaleidoscope   Half-n-half Clue   6. change or introduction of novelties.   solstice   innovation   miasma   sextant   Half-n-half Clue   7. center of turbulence or whirling motion.   solvent   vortex   symmetry   insomnia   Half-n-half Clue