Ron Guth: The 1897-S Quarter Dollar is found with the mintmark in two positions: one with the S above the space between the R of QUARTER and the D of DOLLAR and another with the S above the left edge of the D. Apparently, the first variety (S between the R and D) is the scarcer of the two. Click on the "View All Images" link to see examples of both.
Sources and/or recommended reading:
"Those Shifty Mintmarks" by David Lange, The Numismatist, September 2010, pp. 21-22
Joseph O'Connor, sold privately in 11/2003 - Eugene H. Gardner Collection - Heritage 5/2015:98402, $36,425
Craig M. Morgan, M.D. Collection - Bowers & Merena 11/1998:147 - Eugene H. Gardner Collection, Part IV - Heritage 10/2015:98563, $21,150
Heritage 9/2013:6372, $15,275