Missing Clad Layer: Some Bicentennial Quarters were minted without the outer clad layer, giving them a distinct partially silver appearance.
1976-S Silver Proof Quarter: Minted in San Francisco and containing 40% silver, these quarters are especially prized for their composition and historical significance.
Broadstrike Error: This error occurs when a coin is struck without a collar, resulting in a larger and less defined coin.
Doubling on the Reverse: A double die error on the reverse side of the coin creates a unique and noticeable effect.
Inverted Mintmark: An inverted mintmark error, particularly on coins from the San Francisco mint, adds a significant premium to their value.
Unique Variations and Die Varieties: Various other unique minting errors and die varieties also contribute to the high value of some Bicentennial Quarters.