Ancient Document

[Aldebaran]

http://books.google.com/books?id=y7q_AA ... +whetstone
If in the findarkansas search word and / or belgian Whetstone, etc., you will realize that this ancient document already 'people had understood that the Arkansas and COTICULE should be investigated in accordance with the properties' of Their abrasive, and not quantity 'of them.
But studosi era made a mistake by defining the structure of Belgium is very similar to quartz.
Obviously with an optical microscope (I think) must have seen the scratches left on the bevel of the two stones and because they seem like must have thought that the hardness was the same.