An Elder in Pond Inlet shared a story with me about a man who had a disastrous time making the move from knapped flint tools to ground stone blades. The man had made many flint tools in his life and he always checked their sharpness by holding them up to the light and looking through the edge. When the flint was sharp, the edge was so thin that he could see through it. One day, he tried a new material that was softer than flint and decided to try grinding it sharp into a saw blade. This was his first time seeing this type of material.
Sharp slate knives are not translucent
He started grinding the soft stone and every once in a while, he'd stop and hold the edge up to the sun to see if it was translucent and sharp as flint yet. He worked and worked for hours, but he could never see the sun through the edge of the saw and he considered it not sharp enough to satisfy his ego. Eventually he became so frustrated that he swiped the blade against his hand to show how useless it was - and cut through the tendons on four of his fingers!