The coin in question is a 1915 Barber Quarter, a notable piece in the series of quarters designed by Charles E. Barber. Struck at the San Francisco Mint, this quarter features the distinctive mint mark 'S', indicating its origin. The Barber Quarter is made of 90% silver and 10% copper, weighing 6.25 grams and measuring 24.3 millimeters in diameter. With a total mintage of 704,000 pieces, the 1915 Barber Quarter is relatively scarce, contributing to its appeal among collectors. The reverse side of the coin showcases an eagle perched on a shield, while the obverse features a profile of Liberty. This combination of aesthetic appeal and historical value makes the Barber Quarter a sought-after coin in the numismatic community. In summary, the 1915 San Francisco Mint Barber Quarter is a silver coin with a distinctive design, limited mintage, and rich history, making it a valuable addition to any collection of United States coins.