Important Notice: Our web hosting provider recently started charging us for additional visits, which was unexpected. In response, we're seeking donations. Depending on the situation, we may explore different monetization options for our Community and Expert Contributors. It's crucial to provide more returns for their expertise and offer more Expert Validated Answers or AI Validated Answers. Learn more about our hosting issue here.
aka Carborundum- it is the second hardest naturally occuring substance, #9 on the Mohs scale ( Diamond is l0) Corundum is found in Rubies, sapphires, and more prosaically aluminum oxide sandpapers and grinding wheels made by I believe the carborundum division of Union Carbide. they had some connection with General Stilwell who was, after all a C.O.E.
