Chert is NOT quartz

Recently in an arrowhead video comment, I chastised another commenter for confusing chalceonoy with quartz. According to Britannica quartz is - pretty much - anything containing SiO2. So he was right and I was wrong.

However, in consideration of the difference in knapping properties of -say- chalcedony and quartz, the first is a smooth conchoidal fracture material and the second is an un-predictable and brittle material - these two should in no way be considered the same thing. Because in arrowhead commenting society the knapping properties are significant. I do not think the community uses the word "quartz" the way Britannica does.