[TXnMA]

Piasa, I also appreciated your discourse on patination.

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. However, since hydration rate is strongly affected by the surounding soil (pH, etc.) conditions, I have never relied on it.

But this specimen is supposedly andesite, which is so heterogenous that all patination 'bets are off'...

Thanks again!

[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.'

[piasa]

You don't have to rely on it for aging, but it's a good indicator that something isn't a newly manufactured hoax.