Solve the puzzle

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Across
  1. 4. huge blocks of stones
  2. 5. a kind of stone that chips easily
  3. 6. used to make needles blades and other tools
  4. 7. darwin a renowned biologist
Down
  1. 1. small stones
  2. 2. used to draw carts
  3. 3. a means of getting food
  4. 6. an alloy of copper and tin