This coin is a 2006 San Francisco Mint Sacagawea Dollar, a part of the United States dollar coin series that honors the historical figure Sacagawea, who served as a guide and interpreter for the Lewis and Clark Expedition. This particular piece is a Proof coin, known for its high-quality strike and mirror-like finish that enhances its beautiful design. The coin has a diameter of 26.5 mm and a weight of approximately 8.07 grams, crafted from a Manganese-Brass alloy, which gives it a distinctive golden hue. Its mintage is relatively moderate at 3,054,436 coins produced, contributing to its availability among collectors today. As a currency, this coin is valued at $1, but its true worth may vary in the numismatic market based on its condition and demand among collectors. The San Francisco mint mark (denoted by an "S" on the coin) signifies that it was minted in San Francisco, a historical center for coin production. Whether you're a seasoned collector or a newcomer to the hobby, this 2006 Sacagawea Dollar is a notable piece, representing both the rich history of the United States and the artistry of modern coinage.