Fort Lyon, Colo, Mar 10 1874, two strikes of octagon date stamp (Jarrett 109) on 1870, 3¢ green return corner card entire to the Treasury Dept. in Washington D.C., missing backflap and some paper remnants on reverse, otherwise Very Fine, rare and believed to be only two or three examples known of this Fort Lyon postmark. Estimate  $300 - 400. $0 (Image)