Googled Pike Special Washita Oilstone and found the company has been around a good while, some interesting info on how the stone was mined, etc...
This one is a flea market find. The stone measures 3" long, 2" wide and 1" thick. The old paper label actually wraps over on the end of the stone, at first I thought it might have been broken and squared back up, but with the label it probably is factory size. Haven't seen one this size before. There a couple of small dings on the bottom and the stone is a light grey almost white color, may even have a tint of yellow color

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Treefarmer