I recently got this sharpening stone in a lot and I finally started playing with it today. it's 11in ×1 (5/8)x (5/8). I thought it was an artificial stone at first but now I know it's not. It shimmers like glitter and looks like The Rock's you find on the side of the train tracks. Any ideas on what it might be??? I also highly doubt it's a finisher.

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