Related Clues:

• Seemingly unsolvable
• Like a Saturday crossword
• Too complex to solve
• Flinty
• Fatiguing
• 10 on the Mohs scale
• Like some ciders
• Like some water or lemonade
• Part 3 of today's quote
• No piece of cake
• #6
• Like some copies and courts
• High on the Mohs scale
• Raising a lot of doubt
• Cryptic, mysterious