[blam]

"No doubt you are aware that, for suitably homogenous and well-calibrated sources, photomicrographic measurement of the depth of hydration (patination) has proved to be a fair first-order aging technique for flaked obsidian."

I've seen this technique used before and the patination was called 'desert varnish.'

[TXnMA]

I've seen this technique used before and the patination was called 'desert varnish.'

Me, too. Fortunately the desert environment is fairly consistent, so the patination is repeatable. When you throw in things like organic acids and widely varying soil moisture levels (as are common in the forests where I live) the repeatability gets more than a little bit shaky...

TXnMA
Texas Archeological Steward