Discuss whether either of the following contracts will be unenforceable on the ground that voluntary consent is lacking:

Simmons finds a stone in his pasture that he believes to be quartz. Jensen, who also believe the stone is quartz, contracts to purchase it for $10.00. Just before delivery, the stone is discovered to be a diamond worth $1,000.00. Can Simmons void the contract? Why or why not? Argue one way or the other.

Jacoby's barn is burned to the ground. He accuses Goldman's son of arson and threatens to have the prosecutor bring a criminal action unless Goldman agrees to pay him $5,000.00. Goldman agrees to pay. Can Goldman later void the contract? On what grounds?