Abrasives museum--the earliest of grinding or abrasives tools

Recently, Abrasivesman- Xiao did a business trip in somewhere during he visited a local museum and discovered the earliest of abrasives and sanding tools The Photo-1 showed that this is kind of special grinding tool that this is grinding broken of tool. grinding objective may be stone. The photo-2 is a types of abrasive or polishing tool and its shape likes a plate; the grinding objective was on the top and then through use hand sanding. According to this abrasives'museum of introduction, these abrasives or grinding tools have over 2000 years