1992, 29¢ Minerals, silver (litho) omitted. Plate block of 8 with se-tenant strip of 4 error in bottom row, o.g., never hinged, fresh and Very Fine, a great rarity, this being one of only two known strips in existence; with 1994 P.F. certificate. Scott No. 2703b  $8,250. $0 (Image)