High Grade Dendritic Silver Ore from the Alhambra Mine Grant County New Mexico. A book matched pair that weighs 66 grams and was about 3/4" X 1 1/2" X 1 5/8 " inches before cutting. On one edge - at the center - the native Silver has been altered to or replaced by bluish Acanthite - Silver Sulfide.
For more info on this mine - please reaserch USGS bulletin 1009 - K