I was of the opinion that there were a few intelligent, educated FReepers left, but reading down this thread disabuses me of that notion.
As both a physical chemist and an Archaeological Steward for the State of Texas (THC), I must say that the imbecile (or charlatan) who wrote this article most obviously never even took a high school course in chemistry -- or, if they did, they smoked pot during class!
Obviously, they never heard of the fact that, when one etches a line in an isotropic material, the line grows as much in width as it does in depth. A career in microelectronics convinces me that is always the case.
And, hard, tough (non-single-crystal natural stone is anisotropic. Controlled, precision etching of isotropic materials is challenging to control; etching anisotropic materials is basically uncontrollable. (Or, if it is single-crystal, is controlled by the crystal structure, itself.
Most of the harder, tougher natural stones are inhomogenous, polycrystalline agglomerations. To see what a "polished surface" attacking one with an acid would provide, they need only look at their first illustration -- or spill battery acid on concrete...
And, obviously they don't understand that HF is treacherous and dangerous stuff. If it gets on your skin, it diffuses inward and selectively attacks the calcium compounds in your bones -- while leaving little evidence on the skin's surface. Even IF primitive folk managed to form HF (certainly NOT from plants!), how long does anyone here think they would have survived handling it, trying to do what they could do better by bashing on the rock with another rock? (I'm also a lithic technologist and flintknapper; I've bashed a lot of rock...)
This article is high school "F" chemistry student BS!
